Pisa
How Pisa was built and evolved over time
Built on silt, and all of it moves
Everything that makes Pisa famous stands on the same thing: soft, waterlogged, unevenly compacted alluvial deposit laid down by the Arno. Nothing heavy sits on that ground without settling, and the Piazza del Duomo is the most instructive demonstration in Europe of what happens when great architecture is attempted on bad foundations. The campanile is the famous case, but the cathedral and the baptistery lean very slightly too.
The cathedral, and a style that was exported
Work on the cathedral began in , at the height of the republic, and its design is an argument about where Pisa's wealth came from: classical columns, inlay drawn from Islamic sources Pisan ships traded with, and tier upon tier of blind arcading in striped marble. The combination became Pisan Romanesque and spread with Pisan sea power through Tuscany, Corsica and Sardinia. The square itself was laid out on open ground outside the walls, which is why it still feels set apart from the town rather than embedded in it.
The baptistery
Begun in , circular and the largest in Italy, its interior does something no drawing conveys: a sung note sustains long enough to overlap with itself, and the custodians demonstrate it aloud several times an hour. It is the one part of the complex that works on the ear rather than the eye.
The campanile, and why the delays saved it
The bell tower was begun on 9 August 1173 and not finished until 1372 — 199 years. It had already started to settle unevenly before the third storey was complete. Construction halted repeatedly, and those halts are precisely why the tower is still standing: each one let the subsoil consolidate under the load already imposed, which a continuous build would never have allowed. Masons also corrected as they went, which is why the tower is slightly curved rather than straight, and why the bell chamber at the summit was built level on a structure that was not.
It stands 55.86 metres on the low side and 56.67 metres on the high side. By 1990 the tilt had reached 5.5 degrees and the tower was closed; work between 1993 and 2001 — extracting soil from beneath the high side, applying counterweights and anchoring the base — reduced it to 3.97 degrees, where it is now stable and permanently monitored.
The Camposanto, and a roof that burned
The Camposanto Monumentale is a cloister built around a burial ground, and its walls were covered in fourteenth- and fifteenth-century frescoes. In wartime fighting set the roof alight and molten lead ran down over the paintings. The restoration has been running for decades and is still unfinished, which is why the building is simultaneously the quietest in the square and visibly a worksite — and why the adjoining Sinopie Museum exists at all: it holds the preparatory under-drawings exposed when the damaged frescoes were lifted from the walls.