St Paul's Cathedral

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St Paul’s Cathedral is the domed Anglican cathedral on Ludgate Hill, the highest point in the old City of London, designed by Christopher Wren and built between 1675 and 1710 to replace the medieval church gutted in the Great Fire of 1666. It is the seat of the Bishop of London and one of the defining works of English Baroque, crowned by a dome that for roughly two and a half centuries — from its completion until the rise of the broadcasting towers of the early 1960s — was the tallest structure in the city, the ball and cross standing nearly 366 feet above the pavement.

A church on Ludgate Hill since the seventh century

The ground beneath Wren’s building has carried a church far longer than any fabric now standing on it. A cathedral was established here in 604, in the first generation of the Augustinian mission to the English, and the present structure is reckoned the fourth in succession on the hill, the earlier ones lost to fire and to the upheavals of the early medieval centuries. The immediate predecessor was the great Norman and Gothic church now called Old St Paul’s, begun in 1087 and enlarged over more than two hundred years into one of the largest cathedrals in Europe. Its lead-sheathed timber spire, finished in the early fourteenth century and rising — by the figure that comes down to us — some 489 feet, was among the tallest things built in the medieval West, until lightning took the spire in 1561 and it was never replaced.

By the seventeenth century the medieval fabric was decayed, patched, and hemmed about with shops; Wren had already been commissioned to survey it and propose repairs, even toying with crowning it with a dome, when the Great Fire of London settled the question. In September 1666 the fire reached the churchyard, the scaffolding caught, the lead of the roof ran molten into the streets, and the masonry calcined and split. What was left could not be saved. The decision to demolish and rebuild from the ground was not a restoration but the clearing of a site for a wholly new conception — the first cathedral in England raised in a single campaign, to a single controlling design, under a single architect.

The mathematician who became an architect

Wren came to architecture late and from an unusual direction. He had been Gresham Professor of Astronomy in London from 1657 and then Savilian Professor of Astronomy at Oxford from 1661, a founding fellow of the Royal Society — that society later elected him its President, in 1680 — and a working geometer who had studied the cycloid, the resistance of fluids, the rings of Saturn, and the construction of curves. His turn to building grew out of that same cast of mind. Architecture, for Wren, was geometry made to stand up: a problem in proportion, in the resolution of forces, in the ordering of solids in space. His own theory, set down in the memoranda his grandson printed in the Parentalia of 1750, distinguishes two causes of beauty. One he called natural, and located in geometry — in uniformity, that is in equality, and in proportion; the square and the circle he held to be the most beautiful of figures, with the parallelogram and the oval next after them. The other he called customary, bred by habit and familiarity. The natural cause he took to be necessary and unchanging; the customary, a matter of acquired taste. The cathedral is, among other things, an argument for the priority of the first.

The design did not arrive whole. An early scheme on a Greek-cross plan was developed into the celebrated Great Model of 1673 — a wooden model some eighteen feet long, still kept within the cathedral — a centralized, domed composition of an almost Italian boldness that the clergy rejected as too radical and too little like a traditional church. Wren is said to have wept at its refusal. What was actually licensed was the more conventional Warrant Design of 1675, a long-naved cruciform church with a steeple, granted under a royal warrant that allowed the architect to make such variations as he thought “ornamental.” He took the latitude and built, by stages over the following decades, something much closer to the Great Model’s spirit than to the Warrant’s letter. The foundation stone was laid in June 1675; the last stone of the lantern was set in place in 1708 by the architect’s son; and Parliament declared the cathedral complete on Christmas Day, 1711.

The dome: three shells and a hanging chain

The dome is the building’s central solution and its central wonder, and it is a piece of structural reasoning before it is anything else. Wren did not raise a single shell of masonry, which on this span would have had either to be ruinously thick or to thrust its walls apart. He built three nested domes, each doing a different work. The innermost is a shallow masonry cupola, generous enough in its rise to be satisfying from the floor of the crossing and pierced at its crown with an opening. The outermost is the great hemisphere the city sees — a timber frame sheathed in lead, shaped for the skyline and not for the load it appears to carry. Between the two, hidden from every vantage, rises the structural heart of the whole: a tapering cone of brick that bears, on its own slender walls, both the weight of the outer timber dome and the immense stone lantern above, a mass on the order of eight hundred and fifty tons set down upon the cone’s apex.

The geometry of that cone was not guessed. Wren’s colleague at Gresham, Robert Hooke, had stated the governing principle in 1675, publishing it as a Latin anagram whose solution reads, in translation, that as the flexible line hangs, so, inverted, the rigid arch will stand. A chain or cord suspended between two points falls into the curve called the catenary, and carries its load in pure tension; turn that curve upside down and it carries the same load in pure compression, with no tendency to bend the masonry that follows it. The hanging chain finds, of its own weight, the one line along which an arch can stand without thrusting sideways — and a dome is an arch turned about its axis. Wren shaped the brick cone, and drafted the inner and outer domes, to follow such curves rather than the simple hemisphere of the Roman tradition. This is one of the earliest occasions on which a mathematical theory of form was carried directly into the design of a building; the line of the dome is, quite literally, the line of a falling cord read backward. To bind the structure against the outward spread that even a catenary cannot wholly abolish, wrought-iron chains were laid in courses around the base of the cone and the cornice of the inner dome’s gallery — a girdle of iron holding the masonry to its calculated curve.

The drum on which all this rests is encircled, on the outside, by a colonnade of paired columns, and within, at the level where the inner dome springs, by a walkway that has given the building one of its most famous effects. A word spoken low against the curved wall of this gallery travels around its whole circumference and arrives, distinct, at the far side — a consequence of sound running along the concave surface — and from it the gallery takes its name. It stands roughly a hundred feet above the cathedral floor and some two hundred and fifty-nine steps above the entrance, with the outer galleries of the dome higher still.

Wren, the craft, and the rise of speculative Masonry

It is the figure of Wren, and the precise moment of the rebuilding, that draws the cathedral into the esoteric histories of the modern West. St Paul’s rose across exactly the decades in which the lodges of working stonemasons in England were beginning to admit men who had never cut a stone — antiquaries, gentlemen, natural philosophers — and in which the symbolic, “speculative” Freemasonry that would organize itself into a Grand Lodge took shape. The conjunction was too apt to be left alone. Later Masonic tradition claimed the cathedral’s architect as one of its own, naming him a member, even a Grand Master, of the lodge that met near the cathedral and is held to be the ancestor of the body now called the Lodge of Antiquity. The antiquary John Aubrey recorded that Wren was to be “adopted a brother” of the accepted masons in 1691; James Anderson’s Constitutions, in its second edition of 1738, wove him into a continuous line of Grand Masters reaching back through the ages.

The documentary basis for all this is thin, and what there is points the other way. Wren’s name is absent from Anderson’s first edition of 1723 and appears only in the second, fifteen years after Wren’s death, in a narrative composed two decades after the events it claims to describe; Anderson’s account has the London lodges resolving in 1716 to gather under a Grand Master precisely because Wren had neglected them — hardly the testimony of a devoted brother. Critical historians of the Craft, from Albert Mackey in the nineteenth century to Andrew Prescott and Susan Sommers in the present, have treated the whole construction with caution. Much of what the eighteenth-century writers said of Wren and Masonry, Mackey already judged, was without historical confirmation, the dates of his supposed initiation vague and irreconcilable; Prescott and Sommers, re-examining the sources Anderson used to manufacture the Grand Lodge’s pedigree, conclude that he largely got the story wrong. The deeper point is structural. The operative lodges of the building trades, in which men like the master masons of St Paul’s actually worked, are not simply continuous with the gentlemen’s lodges that crystallized after 1717; the genealogy that makes Wren a Freemason in the later, symbolic sense reads a fully formed institution back into a generation that did not yet possess it. The United Grand Lodge of England does not list him among its own.

What is beyond dispute is more interesting than the legend it spawned. The cathedral was raised by working masons steeped in the geometry of the building craft — the square, the level, the plumb, the compasses — the very tools that speculative Masonry would lift out of the workshop and make into emblems of a moral and cosmological order. And it was designed by a man for whom geometry was already half-sacred: a fellow, and later President, of the Royal Society, moving in the circle of Isaac Newton and the new natural philosophy, who held number and proportion to be the natural cause of beauty and the order of the cosmos. The conviction that the fabric of the world is geometrically intelligible was common ground between the mathematician-architect and the symbol-makers of the lodge; they did not need a shared membership to share an inheritance.

That inheritance runs back through the Renaissance reading of Plato and the Pythagorean doctrine, revived through writers like Robert Fludd and John Dee, that the world is built on number and harmonic ratio — a tradition older than the science of Wren’s own century and not wholly displaced by it. Around the cathedral a later literature has grown that reads its measurements, its alignments, and its sculptural program as a coded design, sometimes tying the building to the Newtonian and antiquarian circles in which Wren moved. These readings vary widely in rigor, and the bolder ones outrun the evidence; the building was a working church for the Church of England, set out by a committee of clergy and commissioners as much as by its architect, and its proportions answer to liturgy, sightlines, and the engineering of the dome before they answer to any hidden scheme. What can be said plainly is that St Paul’s belongs to the last moment in which the mathematics of building and the symbolism of the craft were not yet wholly separate, and in which a learned architect could treat geometry as something close to sacred without ceasing to be an engineer.

Texts, scholarship, and the building’s own record

The primary record of Wren’s intentions is the Parentalia: or, Memoirs of the Family of the Wrens, compiled by his son and published by his grandson Stephen Wren in 1750, which preserves the architect’s own essays on architecture and beauty. The fullest modern reconstruction of his scientific formation is the survey of his mathematical work assembled by historians of mathematics; an accessible account of his career as astronomer, geometer, and architect is maintained in the MacTutor History of Mathematics archive. The structural logic of the dome, and its dependence on Hooke’s analysis of the hanging chain, is set out clearly by the University of Cambridge’s Plus magazine. On the contested Masonic genealogy, the indispensable corrective is the revisionist scholarship on the origins of the Grand Lodge — Andrew Prescott and Susan Sommers’s study of Anderson’s account, published through the research lodge Quatuor Coronati, which dismantles the traditional narrative on which the Wren legend rests. Among the standing churches of the West, St Paul’s invites comparison less with the Gothic cathedrals of Bourges, Chartres, Lincoln, and Canterbury, whose masons reached height through the pointed arch and the flying buttress, than with the two great domed churches it consciously answered: Brunelleschi’s octagonal dome at Florence and Michelangelo’s and della Porta’s at St Peter’s in Rome.

Wren lies in the crypt beneath the work, under a plain slab; the inscription his son composed for the wall above ends with the line cut also into the pavement at the center of the church, si monumentum requiris, circumspice — if you seek his monument, look around. The instruction is exact. The monument is not the tomb but the geometry overhead: the inverted hanging chain made permanent in brick, the square and the circle that he called the most beautiful of figures resolved into stone and lead, a single mind’s conviction that the order of number is the order of beauty, carried up two hundred and sixty feet and held there by an iron girdle and a curve that a falling cord had drawn.

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