Domes: the inside story!

 

A view of Brunelleschi's massive dome for Santa Maria del Fiore, the cathedral of Florence, with Giotto's Tower (which doesn't lean!), the cathedral's bell-tower, on the left.  The body of the cathedral is obscured by the parapet of a terrace in the Uffizi, from where the photo was taken. The exterior decoration of the drum of the dome was completed on only one side, visible here as the white section on the right side of the structure. Note the very large 'lantern' on the top. (Photo: the author)

 

In this article, I'd like to have a look at some domes, or to be more precise, the inside of domes. The word itself derives from the Latin domus which means 'house' and seems to have come into English via the Italian word duomo which can also mean 'house of God'. In Italy, duomo is the name commonly given to cathedrals such as the well-known Duomo at Florence, the cathedral of Florence. And like many cathedrals, it happens to have a dome (or, cupola) on top, a particularly famous one. Domes are often shaped like part of a sphere or one end of an egg, and have a circular base but, actually, there are many variations in shape, as we shall see. However, many of the structures which are crowned by a dome are not themselves circular so how does a circular 'roof' sit on a non-circular structure? If the structure is itself circular, such as the Pantheon in Rome (see below), then there's no problem (leaving aside 'statics' of course*); otherwise, a system of 'joins', or morphologically independent supports, is necessary and these are, below the dome: a drum - a round or polygonal structure like a drum - which sits on (normally) four large arches which, in turn, rest on very large and robust piers (or, massive columns). So let's begin.

In fact, there are domes on important buildings all over the word but here we will be concentrating on some in Italy. I would suppose that most people are familiar with the magnificent dome on Saint Peter's basilica in Rome, the principal church of Christendom, and as well, probably the one already mentioned in Florence; but the oldest dome in Rome is the one on top of what was in fact a pagan structure, the Pantheon - a Greek word (πανθειον) meaning '(temple of) all the gods'. That dome is regarded as an engineering marvel (to use a cliché), apparently being made entirely of concrete; the building itself is also interesting because it is circular. To some, it may seem obvious that the main structure beneath a circular 'roof', such as a dome, would also be circular, but, as we shall see, this is not necessarily the most usual situation; indeed, neither Saint Peter's nor the Duomo of Florence is a circular building. The inside of the Pantheon dome is modelled (in concrete) so that it looks like superimposed rings of squares which become gradually smaller and smaller as they approach the opening in the centre.

The Pantheon or Rotunda with its Corinthian columns and triangular pediment; the top of its dome is just visible in this photo but the main circular structure is quite clear. (Photo: the author)

The original temple - if that is what it actually was - is believed to have been built by Agrippa in c.25BC and then rebuilt by the emperor Hadrian between 118 and 128AD. More recent studies however suggest that the emperor Trajan may be, in fact, primarily responsible for what we see today. That said, what we see today is what remains after quite a lot of authorised pillaging (of bronze, columns, statues, marble, etc.), especially from the interior and the dome. The original structure, whether temple or a sanctuary for the gens Julia (of which Julius Caesar was a member), was in any case higher (in relation to street level) than it appears today, as witnessed by the remaining staircase now hidden under the present piazza.

Staying in Roma since we're already there, the next one, a small one, is from one of the churches in the Piazza del Popolo called Santa Maria del Popolo! This small Baroque church is most famous for its two Caravaggio pictures: the Crucifixion of Saint Peter and the Conversion of Saint Paul. Our little dome is an example, of which there are many, where the inside is frescoed with pictures.

Dome on Santa Maria del Popolo, Rome (Photo: the author)

In this image we may note, apart from the fresco decoration, the structure supporting the rather shallow dome: the 'drum' of the dome is actually a polygon made up of walls with large light-carrying windows; as is common, the drum is supported by arches resting on heavy piers.

Also in Rome, in Sant'Andrea al Quirinale, is the next dome, a very elaborate one, both in terms of its decoration and in terms of its structure: it is elliptical in plan and is formed of ten segments, like slices of an orange, and each segment is enlivened with the popular 'honeycomb' pattern of the coffering. The windows at its base are surmounted by 'in-the-round' plaster sculptures of saints and cherubs. Like the church itself, the dome's main axis is parallel to the street. The present beautiful small church and its façade were re-designed by Gian Lorenzo Bernini with construction beginning in 1658 and finishing in 1678. 

The dome of Sant'Andrea al Quirinale; the church was consecrated in 1568 (Photo: the author)

Continuing in much the same direction, still in Rome, we arrive at the marvellous basilica of Sant'Andrea della Valle where those in charge have had the clever idea of mounting large mirrors in the central nave so that visitors can admire the ceiling frescos - without damaging their necks at the same time! This church is what might be described as a 'typical' Baroque enterprise, at least as far as its ceiling decoration goes: the entire surface, including the dome, is frescoed. As with other such domes, this one rests on a fairly high fenestrated drum which in turn sits on four very large arches, visible in the photo, supported by four very large piers; in fact, standing in the crossing, one is reminded of Saint Peter's basilica, though on a smaller scale.

The dome and crossing of Sant'Andrea della Valle in Rome. As can be seen from my iPhone and hands on the right, I was looking into one of the large mirrors situated along the nave.

Continuing in the direction of the Stazione Termini - Rome's main railway station - and passing, because not open, the wonderful church of San Carlo alle Quattro Fontane, a masterpiece by Francesco Borromini, and the comparatively restrained architecture of the church of Santa Susanna alle Terme (still closed after many years), designed by Carlo Maderno in 1603, we find, directly opposite across the piazza, another church masterpiece, this one called San Bernardo alle Terme, whose modern construction commenced in 1598. (And looking back across the piazza, to the right, is the home of one of Bernini's masterpieces, The Ecstasy of Saint Teresa, in the small Baroque church of Santa Maria della Vittoria; Rome supposedly has around 900 churches!).

The dome and oculus of the church of San Bernardo alle Terme, apparently an original Roman structure, a smaller version of the Pantheon type. (Photo: the author)

This smallish church, and its dome, are especially interesting as it occupies one of the two remaining giant towers which were originally situated in the long-gone perimeter walls of the nearby Baths of Diocletian (terme), those remains now a church and museum; this particular tower was apparently a place used for playing ball games (a spheristerium) and its dome is, from what I can discover, part of the original Roman structure. The present church preserves the circular form of the tower and its only source of light, the oculus (the eye, in Latin) in the centre of the dome, exactly the same as occurs in the Pantheon! Apart from the dome with its 'honeycomb' pattern, this church is relatively simple inside but does contain eight gigantic plaster statues of saints, all very good.

Finally, as far as Rome is concerned, I want to include another masterpiece by Francesco Borromini, the church of Sant'Ivo alla Sapienza. Again, after two visits and a long wait for the scheduled opening time, disappointment: I wasn't able to see inside! However, the exterior of the church is fantastic (literally) and the four-sided, two-storey courtyard is wonderful. The first architect whose name I can find was Pirro Ligorio (1565), followed by Giacomo della Porta (1579) - responsible for the courtyard buildings - who in turn was followed by Borromini in 1632 (although the complex dates back to the foundation of the University of Rome in 1303).

The courtyard and façade of Sant'Ivo alla Sapienza in Rome. (Photo: the author)

From what I have read, the design of Saint Ivo is unique in church architecture as it is based on the triangle! Each of the corners (of the triangles) is cut by a semi-circular shape - creating chapels - turning the floor-plan into a six-sided figure; the segmented 'dome' has a lantern with a spiralling top on it. The photo above gives at least some idea of what may be inside but, to know for sure ... well, that's another trip, isn't it?

Now we move north to Tuscany and begin in an ancient hill-top city called San Miniato. At certain times in its history it was quite a rich place and this can be seen in the wonderful interior of one of its churches, the Santuario del Santissimo Crocifisso (the Sanctuary of the Most Holy Cross).

The Santuario del Santissimo Crocifisso (built 1705 - 1718) in San Miniato: photo (by the author) showing the frescoed dome above the crossing, supported by a drum, arches and massive piers. 

Recently restored and looking wonderful in the early-summer sunlight, this smallish Baroque structure is situated on a steep hill in the centre of San Miniato. Although quite restrained externally, once inside, all stops are out and the eye feasts on a mini version of some of the great Roman churches: everywhere is painted, and decorated with statues, especially the main and two lesser altars, the latter being adorned with wonderful trompe l'œil columns and angels. This time we have a circular dome resting on a circular fenestrated drum.

Closer to Florence, in the church of the Badia delle Sante Flora e Lucilla in Arezzo, is our next example: the dome is not large and, in reality, is not a dome at all! It is a painting of the interior of a dome, an oil painting on a large circular canvas, a brilliantly contrived perspective exercise, designed to do duty for the more expensive real thing! The illusion is so convincing that, if you weren't really paying attention, you could easily walk out of that church convinced that it had a largish, dark dome. The canvas, which includes a painted oculus, sits exactly where a physical dome would sit, thereby increasing the sense of its 'reality'. The illusion is of a segmented circular structure supported by a drum composed of columns and windows.

Fictive dome of the Badia church in Arezzo, oil (?) on a circular canvas imitating an earlier one (1685) by Andrea Pozzo in Rome in the church of Sant'Ignazio di Loyola (Photo: the author)

Having arrived in Florence itself, rather than going off to visit the incredible dome of the Duomo, designed by Filippo Brunelleschi (1377 - 1446), let's cross the Arno and, on the south side of the river, visit the lively Piazza Santo Spirito and its homonymously-named church of ... Santo Spirito! This is one of my favourite churches in Florence, not only because it too was designed by Brunelleschi (from1434) but also because it is, as are so many churches, a sort of art history lesson, or a museum - without actually being one! Its many side-altars are decorated with altarpieces painted by important artists, it has a vestibule designed by Andrea Sansovino and a sacristy designed by Giuliano da Sangallo, as well as a beautiful garden in the centre of its cloister.

The dome of Santo Spirito in Florence, designed by Filippo Brunelleschi (Photo: the author)

Again, a small dome above a crossing (where the nave meets the transepts of a church), unlike the massive one over Santa Maria del Fiore - the Duomo of Florence - but very similar to those in his Cappella Pazzi at Santa Croce and Sagrestia Vecchia at San Lorenzo, both churches in Florence. In the photo we can also see the coffered ceilings as well as the huge arches which support the dome and its small, elegant drum. This dome (note the round windows), like others, is made-up of segments but, as is typical of Brunelleschi - and interestingly, of his anticipation of one of Modernism's dicta, 'truth to materials' - it is unadorned, like the arches and in fact, like all the structural elements of this building. Brunelleschi, unlike later Baroque masters, wanted us to see what was in fact there, he didn't want to conceal the architectural 'members' under layers of stucco (plaster) and paint; he didn't want his elegant, refined lines and curves muddled and distorted by accumulations of decorative illusion.

Before leaving Florence, we must have a brief look at another structure which, although not strictly a dome from the outside, is a related architectural construction: this is the baptistry of Florence,  the Battistero di San Giovanni Battista, directly opposite the main entrance to the Duomo. Referred to even by Dante, a very old building whose history is still a matter of some dispute, the baptistry would seem to be one of the oldest Christian religious structures in the city (possibly IV-V century AD). It is an octagon having three entrances and a centrally raised roof constructed in sections to coincide with the eight walls. The exterior of this temple-like building is remarkable enough (with 'Mondrian-like' geometric patterning in white and green marble) but the interior decoration, and especially that of the ceiling, is literally wonderful.

A view of the interior of the dome or cupola of the recently restored Baptistry of Saint John the Baptist showing a part of the extraordinary mosaic decoration, some at least believed to be by Cimabue

A short distance from Florence is the beautiful small city of Pistoia, our next destination. Here, the large exterior dome of the smallish octagonal basilica of Santa Maria dell'Umiltà, designed by Giorgio Vasari (completed 1569), is clearly modelled on that of Brunelleschi's dome for Florence cathedral. But the interior of the dome is very interesting as it seems to contain no overt religious symbolism at all; and the same can be said for the smaller dome pictured here, decorated with concentric rows of small squares in each of which is a flower; the four pendentives, painted red, are further decorated with a large shell: both shells and flowers have a long history of symbolic meanings, Christian yes, but also pagan (for instance, the shell which carries the goddess in Botticelli's Birth of Venus). I don't know whether or not Vasari is responsible for this dome over the vestibule of the church, but it is an extremely elegant and virtually secular solution!

One of the domes in the Basilica of Santa Maria dell'Umiltà in Pistoia, this one over the vestibule (Photo: the author)

To conclude, we hop on a train and head south, to the wonderful island of Sicily where we get off at Catania, on the east coast. Catania is a beautiful city, full of Baroque churches, many lovely black-and-white palazzi, incredible views (not least of its neighbour Etna) and .... food! As everyone knows, Sicily has been occupied by people from all over the place, from the Greeks to the Romans, from the Arabs to the Normans to the Spanish; all have left their mark and the first dome we are to have a look at was in fact part of a Roman baths. 

A view of the Terme alla Rotonda in Catania, taken from outside (Photo: the author).

In the photo, we are standing among the remains of various rooms which were once part of the baths (terme); clearly, the dome has been strengthened since ancient times. It has changed uses over the centuries and was at one time a church (Santa Maria della Rotonda); it contains medieval frescos as well as much later, painted decoration and inscriptions, and is still an active archeological site.

 

An interior view of La Rotonda: large niches open in the thick and heavy walls supporting the dome and the floor level was, at the time of the photo, still open for excavation. (Photo: the author)

Still in Catania, and a little further up the hill, in fact, on what is locally known as l'acropoli (the acropolis: remembering that Catania was once Greek!), that is, the highest point of the city, we arrive at the spectacular, if unfinished, church of San Nicolò l'Arena, with its impressive monastic complex behind (now a university). The interior of this very big church is surprisingly, almost alarmingly, sedate, quite unlike many of the Baroque - and Norman - churches which are to be found all over the island. Above the crossing however is a quite plane, unadorned dome resting on a fenestrated drum.

The interior, showing the light-giving dome, of San Nicolò l'Arena in Catania. Note the lovely marble floor; the church is dedicated to the fallen soldiers of various conflicts. (Photo:the author)

The photo above shows the relatively small but elegant dome, and largish drum, of San Nicolò l'Arena from the outside, in fact, from the roof, as it is possible to access that area by way of one of the unfinished towers at the front of the building; up there, we have a 360 degree view of Catania, of the sea and of Etna - which is still quite active. In my opinion, the exterior of this dome is the more impressive aspect, together with its refined colour!

Travelling now to the north-west coast of Sicily, we reach Palermo, the site of several important and wonderful Norman churches: but today, we are going to have a look at one more Baroque example: Santa Caterina d'Alessandria, built between 1566 and 1596.

The church of Santa Caterina d'Alessandria, Palermo (Photo: the author)

The almost overwhelming, extraordinary interior - even by Baroque standards - of this church turns into a kind of 'architectural cassata' what is essentially the basic basilica model: a long nave with arched side-chapels leading to a crossing beyond which is an apse. Over the crossing is the dome resting on large arches supported by very large piers; in this case, the dome is on top of a circular fenestrated drum which allows light to enter. The somewhat unusual feature here is the trompe l'œil frescos whose figures actually seem to tumble out of the dome proper and into the drum; this theatricality continues into the pendentives, further contributing to the Baroque habit of so confusing the eye that, at a certain point, we are no longer quite sure about which parts are 'real' and which are artifice! Like many important buildings in Italy, this one was damaged by bombing during the Allied invasion of WWII and the missing parts of the frescos just mentioned may be a result of that bombardment. Thankfully, much restoration - and some discovery - has brought many of these buildings back to their original glory.

* In the first paragraph, I mentioned the word 'statics'; statics is that branch of engineering which considers the implications of weight on the vertical and lateral equilibrium (stability) of buildings. A good example is the so-called 'flying buttress' of Gothic cathedrals: those buttresses 'push' against the walls of the building, walls which are receiving downward and outward pressure (or thrust) from the heavy structure resting on them, namely, the roof. It has been discovered that in the construction of the Pantheon, the exterior walls are actually higher than the inside view of the dome would suggest; this extra exterior height provides a kind of hidden buttressing against the weight of the dome. The concrete dome itself was constructed using a variable recipe for the concrete, allowing the dome to be ever lighter as it reached up towards the oculus. A similar 'hidden' buttressing system is used in the walls of the Baptistry of San Giovanni in Florence.