On 2 September 1666 a fire started in a bakery in Pudding Lane, in London. It burned for four days. It destroyed about 13,000 houses, 87 parish churches and the old cathedral of St Paul, medieval and already in very poor condition. Five days after the fire, Christopher Wren (1632–1723), professor of astronomy at Oxford and a founding member of the Royal Society, presented King Charles II with a plan to redraw the city: wide straight streets, great squares, churches as perspective foci. It would not be carried out: the plot owners wanted to rebuild at once, on the old boundaries. But in 1669 the king appointed him surveyor of the king's works, and for almost half a century the new London passed through his pencil.
Wren came to architecture late and by another road. At Oxford he studied mathematics and astronomy, designed scientific instruments, carried out anatomy experiments. His first building, the Sheldonian Theatre in Oxford (1664–69), is a theatre for university ceremonies with a flat ceiling spanning 21 metres, carried on timber trusses designed by geometric calculation. A trip to Paris in 1665, where he met Bernini and studied the works of François Mansart, showed him continental Baroque. He took from it what he needed: rationality and measure, never theatricality.
Rebuilding without redesigning
Wren's plan was not carried out, but rebuilt London was not the same as before. In 1667 Parliament passed the Rebuilding Act, a law that, instead of redrawing the city plan, set rules for what could be built on it. Houses had to be of brick or stone, no longer timber; they were divided into four classes, according to the importance of the street they faced, and for each the law set the number of storeys and the thickness of the walls. Some streets were widened and the land along the Thames cleared. It was a typically English solution: not a grand design imposed from above, but rules that, applied plot by plot, changed the character of the city. Anyone who has read the history of Roman insulae will recognise the same logic as Nero's regulations after the fire of 64.
Wren did not work alone. His main collaborator was Robert Hooke, a brilliant scientist, curator of experiments at the Royal Society and appointed Surveyor to the City for the rebuilding: together they measured plots, settled disputes between owners and designed many of the churches. The most visible sign of their collaboration is the Monument (1671–1677), a Doric column about 61 metres high, erected about 61 metres from the spot where the fire had broken out. It is not only a memorial: the hollow shaft was also conceived as a scientific instrument, a large vertical telescope for observing stars at the zenith, with a laboratory below ground for experiments. Astronomy and the rebuilding of London were never really separate in Wren's life.
St Paul's: three domes in one
The rebuilding of St Paul's occupied Wren from 1670 to 1711. The first design, in the form of a Greek cross, was rejected by the clergy, who wanted a traditional Latin cross: Wren yielded, but in the final version managed to keep a great dome. The problem is technical and aesthetic. A dome so tall must appear monumental from outside, and inside it must be proportioned to the space below: the two requirements lead to two different heights. Wren solves it by building three shells. An inner shell of brick, low, visible from the nave. A brick cone rising above and carrying the weight of the lantern. An outer shell in timber, covered in lead, that gives the dome its tall profile and the skyline. From inside you do not see the timber, and from outside you do not see the structure.
The path leading to this solution is better documented than that of almost any other cathedral. In 1673–1674 Wren had the Great Model built, a large oak model more than six metres long, showing the Greek-cross design with a central dome; it is still kept in the cathedral and is one of the most important architectural models of the 17th century. When the clergy rejected it, Wren submitted a compromise design, the so-called Warrant Design, approved in 1675, with a Latin cross and even a spire above the dome. But the royal warrant gave him freedom to make "ornamental" variations during construction, and Wren used it very liberally: the building as built moved progressively away from the approved design, all the way to the great dome we know.
The structure also conceals many ingenious solutions. The walls of the upper storey of the aisles are in fact screen walls: behind them, invisible from the street, run flying buttresses that counter the thrust of the vaults, as in a Gothic cathedral, but without showing it. At the base of the cone carrying the lantern Wren had an iron chain inserted, a ring that restrains the structure's tendency to spread outwards. The very form of the cone owes much to an insight of Hooke's, who in 1675 had formulated the principle that the ideal shape of an arch is obtained by inverting the curve of a hanging chain: a suspended chain works only in tension, and the same curve turned upside down works only in compression, the ideal condition for masonry.
The dome of St Paul's, 111 metres to the cross, remained the tallest building in London until 1963. Inside, the Whispering Gallery, a circular balcony at about 30 metres up, lets someone whispering against the wall be heard clearly by someone on the opposite side, 34 metres away. Outside, the drum surrounded by columns and the two western bell towers, added from 1705, make the building a single Baroque volume, sober but monumental. The first stone was laid in 1675; in 1708 Wren's son, Christopher junior, laid the last stone of the lantern; Parliament declared the cathedral complete in 1711.
In the 20th century the dome also became a symbol. During the German bombing of London, the Blitz, a group of volunteers, the St Paul's Watch, kept guard over the roofs every night to put out incendiary bombs before the fire could spread. On the night of 29 December 1940, one of the most devastating, the photographer Herbert Mason took from the roof of the Daily Mail the picture of the dome rising intact from the smoke and flames of the burning City. Published under the title "War's Greatest Picture", it became one of the most famous photographs of the war. The cathedral was hit several times but survived, while many of Wren's churches around it were destroyed.
Fifty-one churches and a city
In the same period Wren directed the rebuilding of fifty-one of the churches destroyed by the fire in the City, each on a narrow, irregular plot squeezed between buildings. Each church is a different solution: a Greek-cross plan at Saint Stephen Walbrook, towers with slender spires that punctuate the skyline (Saint Bride, Saint Mary-le-Bow), timber vaults on slender piers. Together with the cathedral they form an urban landscape in which the spires draw a rhythm around the great dome. Many were destroyed by the bombing of 1940–41; about twenty still stand today in substantially original form.
Three churches help to show the variety of these solutions. St Stephen Walbrook (1672–1679) hides a surprising interior behind a modest façade: a coffered dome resting on eight arches and sixteen columns, in a space that combines longitudinal and central plans. It is regarded as a dress rehearsal for the dome of St Paul's, built a few years earlier and a few blocks away. The steeple of St Mary-le-Bow, with superimposed orders tapering upwards, houses the Bow bells: according to tradition, only those born within earshot of them are true "cockneys". St Bride's, with its ever smaller tiers, is said, in a widespread but undocumented story, to have inspired a local baker to give the wedding cake its tiered form. True or legendary, these stories show how deeply Wren's steeples entered the everyday life of the city.
Beyond London: the astronomer and the king
Wren's work goes far beyond the City. In 1675–1676 he designed the Royal Observatory at Greenwich, commissioned by Charles II to solve the problem of determining longitude at sea: a compact building with a large octagonal room with tall windows, designed for telescopes. It is perhaps the work that most directly unites his two lives, as scientist and architect. At Cambridge he built the library of Trinity College (1676–1695), where the books are arranged on shelves perpendicular to the walls and light comes from high windows above the shelves themselves. In London he designed the Royal Hospital Chelsea for army veterans and worked on the palace of Hampton Court.
The most scenographic project is the Royal Hospital at Greenwich, for disabled seamen, begun in the 1690s. Wren would have liked a single large building with a central dome, but Queen Mary II set a condition: the view from the river to the Queen's House, the small villa designed decades earlier by Inigo Jones, must not be blocked. Wren therefore split the complex into two symmetrical halves, separated by a large central void framing the Queen's House, and placed twin domes on either side of this axis. The constraint imposed by the client became the project's strength: it is one of the most successful Baroque compositions in England, and today forms part of the Maritime Greenwich UNESCO World Heritage Site.
Visitors to St Paul's can physically follow the structure described above. Climbing 257 steps takes you to the Whispering Gallery, inside the dome; continuing, you reach the Stone Gallery, outside at the base of the drum, and finally, after 528 steps in all, the Golden Gallery beneath the lantern, about 85 metres up. On the way, in some stretches, you pass through the space between the inner and outer shells, and understand in a very concrete way that the dome seen from the nave and the dome seen from the city are two different objects. In the crypt, below the floor, Wren's tomb is a simple slab, with the Latin inscription inviting the visitor to look around. The same words are also inscribed in the cathedral floor, at the centre, directly beneath the dome: the best spot from which to follow the advice. The same words are also inscribed in the cathedral floor, at the centre, directly beneath the dome: the best spot from which to follow the advice.