In concept the Campidoglio is simple. Set into the depression between the two peaks of the Capitoline Hill, it is nothing more than three buildings and a central statue arranged to create a small, quiet square. But its historical importance can scarcely be overestimated, for in its day it represented a tremendous leap forward for both urbanism and architecture.
The raw materials were not promising. In 1537, when Pope Paul III first proposed renovating the piazza and transferring the bronze equestrian statue of Marcus Aurelius from the Lateran, the site was a gully-scarred, mud-prone open space bordered by a church and two medieval palazzi.
Stylistically, the buildings were chaotic, and their placement around the central space was completely haphazard: the facades of the two palazzi formed an awkward 80-degree angle, while the facade of the church – a short distance away oon the north peak – did not face the square at all. Moreover, renovation problems were formidable. All the buildings were still in use and funds for rebuilding were limited, so any new scheme had to leave the existing structures intact and allow for their continued use during remodeling. Finally, the site lacked paved access from the northwest, which isolated it from the working city.
Recognizing the difficulties these problems presented, Pope Paull III called in Michelangelo. Sixty-two years old and turning his hand to Roman architecture for the first time, the sculptor took this jumble of leftovers and constraints and produced Rome's first true modern piazza.
Michelangelo's basic idea was revolutionary. Up to that time, Renaissance architecture had been very much a matter of single, isolated buildings. Occasionally several important structures were purposely placed around a central open space, but the aim was to display each individual building to maximum advantage, not to relate it to its neighbors and create an aesthetically unified whole. Michelangelo's concept of a building ensemble – an out-door interior, as it were, where the exterior walls of a group of buildings shape an outdoor space the way interior walls shape a room – was utterly new. [Note that the side buildings in the etching immediately above are canted outward by the artist in order to show the facades, but in reality the buildings are canted inward, as shown on the plan below.]
The details of Michelangelo's design were every bit as revolutionary as its underlying idea. Ignoring the pervasive Renaissance believe that the circle and the square were philosophically "perfect" and therefore the most aesthetically pleasing geometric forms, Michelangelo took as his ruling ground-plan shapes a trapezoid and an oval. Moreover, he used these forms in a way that earlier Renaissance architects would probably have deplored: despite their disparate shapes, he placed the one inside the other. And – more importantly – he gave each shape its own separate focal point, thereby rejecting the traditional central, single-point focus that had been the obsession of Renaissance vision since the invention of one-point perspective in painting.
The first focal point (and the most obvious to anyone approaching the square up Michelangelo's long, sloping ramp known as the cordonata) is the facade of the Palazzo del Senatore. To emphasize it as the dominant side of the his trapezoid, Michelangelo redesigned the facade and moved the building's existing bell tower from off-center left to the building's center, directly over the main doorway and in line with the cordonata.
To de-emphasize the existing Palazzo dei Conservatori on the right, he gave it a new facade. Though similar in many details to the facade of the Palazzo del Senatore, the new design employed a ground-floor portico to hide the building's main doorway in deep shadow so its entrance would not compete with the Palazzo del Senatore.
To complete the trapezoid, Michelangelo placed an entirely new building to the left of the Palazzo del Senatore. The purpose of this new building was purely aesthetic: to hide the facade of the older church and to supply the Palazzo dei Conservatori opposite with a mirror image twin.
The new building had no practical function and was only one room deep, and Michelangelo never even gave it a name (to this day it is known as the "Palazzo Nuovo" – the new palazzo). Its lack of function notwithstanding, it is a critical element in the trapezoidal composition, for when entering the square from the cordonata, the two identical facades function as an extension of the approach ramp, opening out to focus attention firmly on the Palazzo del Senatore.
The second focal point is the statue of Marcus Aurelius in the middle of the square. (The statue now in place is a copy; the famous original survived the vicissitudes of time and history for eighteen centuries – it escaped being melted down in the Middle Ages because it was thought to be a statue of Constantine, the first Christian emperor – but in recent decades Rome's acid-air pollution began to take a deadly toll, and the statue was moved inside the Capitoline Museum in the Palazzo dei Conservatori.)
The statue is set in the center of its own spatial composition: the oval within the trapezoid The shallow steps that define the oval serve two purposes: they give the oval a strong border and they highlight the statue by allowing the ground to rise back to its original level as it approaches the statue. As with the Palazzo Nuovo, the oval's steps – and its decorative pavement – have no practical purpose. They merely serve to give the statue an architectural framework of its own – to expand the oval space commanded by the statue so that it is commensurate with the trapezoidal space created by the buildings.
The use of two focal points creates a tension – where does they eye settle to rest? – that pervades the entire piazza. Where the eye is drawn depends upon which entrance is used. From the main entrance up the ramp, the facade of the Palazzo del Senatore will dominate . . .
. . . From the side entrances, the statue of Marcus Aurelius will dominate. Once inside the piazza, however, the relative weight of the focal points will vary as the viewer moves around the square. Yet no matter what the vantage point, the competition between statue and facade is never lopsided, never unbalanced. It is a superb spatial balancing act.
Michelangelo's radical architectural thesis – that tension is not incompatible with balance – was by no means limited to multistructure compositions. He applied it to single buildings as well. The matching facades of the side palaces, for instance, employ the Classical vocabulary in a double-edged way that was distinctly unconventional. To Michelangelo's eye, Rome's most important Renaissance palazzi probably looked ponderous and overbearing, weighted down by the excessive horizontality produced by their long, tiered rows of regularly placed windows.
To counterweight his own design's horizontal elements, he introduced something rarely seen before in Rome: giant pilasters that cut cleanly through the ground-floor entablature and soar straight up to the building's cornice.
Earlier architects had experimented with giants pilasters, but the resulting mix of scales – two-story pilasters next to one-story columns – tended to look chaotic, almost as if the parts of two different-sized buildings had been combined willy-nilly. Michelangelo succeeded in combining these apparently disparate elements in a way that appears orderly and logical; indeed, his giant pilasters are a key feature of the design, for they give his facade the strong vertical emphasis that earlier facades lack.
And again, a double focus results. It is possible to read the facade in the traditional way, as a composition of three dissimilar horizontals (open ground floor, closed upper floor, cornice). But it is also possible to read it in the opposite way, as seven similar two-story verticals (the bays delimited by the eight pilasters). Paradoxically, this duality increases rather than decreases the facade's overall unity, locking all the visual elements together into a powerful latticework of horizontals and verticals.
And as a closer look at the giant pilasters will reveal, Michelangelo modeled that latticework with special care. The pilasters depart from prevailing convention in a subtle but crucial way: rather than being set directly into the wall, they are set into slightly wider piers, which are in turn set into the wall behind. This small but critical adjustment – a tiny extra step forward from the underlying wall – produces an increase in slimness and relief that gives the pilasters both added elegance and added power. As a result, the pilasters possess a special (and unprecedented) sculptural presence, a presence that was shortly to become one of the defining characteristics of the new Baroque style in architecture.
With the facade of the Palazzo del Senatore, Michelangelo faced an added problem: how to relate the three-story building in the center of the composition to the two two-story buildings on either side. His solution was typically ingenious: he hid the building's ground floor behind a double staircase running most of the length of the building.
The staircase is a visual masterstroke, for it transforms a three-story building into a two-story building raised on a podium and thereby allows the use of two-story giant pilasters on the rest of the facade, just as on the side palaces. Moreover, the staircase itself serves to tie the three buildings together, for its two wings seem to reach out to the side palaces like outspread arms.
Michelangelo's unconventional use of geometric forms and Classical detailing ran counter to most of the accepted theory of the High Renaissance, which sought to revive and improve upon the architecture of ancient Rome as outlined in the newly rediscovered writing of the ancient architect Vitruvius. But the goal of historical and philosophical correctitude, with its rigorous rules and regulations governing the use of the Classical orders, meant little to Michelangelo. His vision was ruled by something else entirely: his sculptor's eye.
With his architecture, the historical and philosophical question "Is it correct?" was overruled for the first time by the question, "How does it look?" This was a radical shift in emphasis – a shift that signaled the end of the Renaissance era in architecure. As Michelangelo's compatriot (and biographer) Giorio Vasari stated, "He proceeded quite differently in proportion, composition, and rules from what others had done . . . whence artisans have been infinitely and perpetually indebted to him because he broke the bonds and chains of a way of working that had become habitual by common usage."
When Michelangelo died in 1564, construction of the Campidoglio was far from complete, and his successor architect, Giacomo della Porta, changed the design in two significant ways.
First, he altered Michelangelo's side-palace window scheme by redesigning and enlarging each palace's central window, giving the facades a central focus. The windows themselves are far from displeasing, but their impact on the facades is unfortunate: they effectively punch a large hole into the middle of Michelangelo's carefully constructed network of balanced verticals and horizontals.
Second, Della Porta radically altered the design for the facade of the Palazzo del Senatore. Michelangelo's scheme called for an upper story that was almost identical to the uppers stories of the side palaces; Della Porta substituted a simple row of plain, small rectangular windows placed high on the facade. The new window design created an awkward empty space below, which Della Porta partially filled with a decorative plaque and two carved crests. Michelangelo's design, by contrast, employed no such decorations because it contained no such awkward empty space.
Happily, Della Porta's modifications are not critical to the overall effect of the piazza. But the familial likeness between the Palazzo del Senatore and the two side palaces is considerably reduced – the twins' older brother, as it were, is now merely a distant cousin.
When it was built, the Campidoglio was an unprecedented architectural tour de force, and it remains one of Western architecture's greatest urban set pieces to this day. And from a historical point of view Michelangelo's two-fold achievement is unique. With his overall plan, he created Europe's first aesthetically unified multistructured urban enclosure; with his innovative use of Classical detail, he overthrew the dictates of Renaissance architectural theory in favor of the subjective vision of his artist's eye. He broke through to a new vision on two artistic fronts at the same time, and he became, as a result, the father of both modern city planning and the Baroque style of architecture.
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One additional sight: The full, formal splendor of the Campidoglio is best experienced at the top of the cordonata, where all the compositional elements can be taken in at once. One special feature of the view, however, is not immediately apparent. A literal turnabout is required: when standing at the top of the staircase facing the Palazzo del Senatore, turn around and look across the street.
Atop the building opposite, some forgotten architect (builder? owner?) has transformed a chaotic cluster of utilitarian chimneys into a miniature hilltop village. Amid the grandeur of the Campidoglio, the sight is completely unexpected, and the surprise is wholly captivating.
In most settings such a conceit would be little more than a gracious urban pleasantry, but placed just here – set apart from the Campidoglio by nothing more than an intervening void – the gesture produces one of the most unusual and unexpected architectural dialogues in the entire city. All sorts of fundamental architectural oppositions suddenly snap into focus: Renaissance vs. Medieval, Classical vs. picturesque, order vs. disorder, function vs. decoration, noble vs. humble. Compared to the grand declamation of the Campidoglio, the voice of the rooftop village is the merest of whispers, but its beguiling message – "this, too, is architecture" – is at this particular spot especially appropriate and especially welcome.