A causeway built by fascist Italy still carries Venice's only road

A rebuilt causeway remains Venice's only road entrance

You are standing near the land end of the Ponte della Libertà corridor, at the seam where Venice stops being an island city and becomes, briefly, a place cars can reach. The street names around you — Fondamenta Santa Chiara, Fondamenta Sant'Andrea, Campo Sant'Andrea — belong to the old Santa Croce fringe, but the ground itself was reshaped in the twentieth century for a single purpose: getting the mainland onto the lagoon. The Ponte della Libertà, opened as a rail causeway in the 1840s and rebuilt for motor traffic in 1933, remains the only land approach to historic Venice, and it lands almost exactly where you are.

A short distance southeast, Ponte della Costituzione — Santiago Calatrava's glass-and-steel arc across the Grand Canal — opened in 2008 amid public argument over its cost and its slippery treads, the fourth and most contested bridge ever thrown across that water. It ties Piazzale Roma to the railway terminus, meaning the patch of pavement under your feet has spent nearly two centuries as Venice's threshold: the point where every train, bus, and car trip into the city has to stop, because no vehicle goes further.

A few streets away, the Università Iuav di Venezia occupies former convent and warehouse buildings, founded in 1926 as one of Italy's first schools of architecture — fitting, in a district built almost entirely from later engineering rather than medieval stone. Overhead and to the west, the automated People Mover glides between Piazzale Roma and the car-park island of Tronchetto, a piece of infrastructure so recent it barely counts as history yet, but it marks the same logic that built the causeway a century earlier: keep the wheels outside, let the water do the rest.

Churches nearby were rebuilt, demolished, or put to other use

Two hundred metres off, the church of Sant'Andrea della Zirada was founded in 1329 by four noblewomen on a spot known as "cao de zirada" — the head of the turn, where boats swung around the bend of the canal. Its Gothic façade survives a 1475 rebuilding, carrying two fourteenth-century reliefs of Christ as Man of Sorrows and Christ calling Peter and Andrew from their boat.

Half a kilometre south, Santa Maria Maggiore, Venice began as a convent church around 1500, only to be deconsecrated under Napoleonic rule and pressed into service, in turn, as a stable, a tobacco warehouse, and finally a prison — an unusually hard fall for a building raised to God.

The church of Santa Lucia, which once stood where the railway terminus now does, was demolished in 1861 to make way for the station that still carries its name — so the saint survives only as a place-name over the tracks. Nearby, San Simeone Piccolo's domed front still faces that station across the Grand Canal, the first or last thing most visitors to Venice ever see.

A kilometre or so east, this stretch of the lagoon briefly belonged to the short-lived Republic of San Marco, the revolutionary state that held out against Habsburg Austria for seventeen months in 1848–49 before the old Republic's territory was folded back into empire and then, later, into Italy.

Closer to the station, the Ponte degli Scalzi — "bridge of the barefoot monks" — was completed in 1934 to a design by Eugenio Miozzi, replacing an Austrian iron bridge that had stood there since the occupation years, another small erasure of the Habsburg imprint on the city.

A canal gateway gave way to a railway causeway

Before any bridge existed at all, boats bound for Venice entered by the Cannaregio Canal, the city's main gateway until the railway causeway of 1846 made the approach overland. The Ponte dei Tre Archi, one of Venice's few multi-arched bridges, still crosses it near San Giobbe, a fifteenth-century church founded on the canal's southern bank in a district once thick with shipwrights and, later, with the Jewish community confined to the nearby Ghetto.

Underneath all of it — the causeway, the glass bridge, the vanished churches — lies nothing so dramatic as bedrock: Venice and its lagoon rest on submarine continental crust, sediment laid down where a river delta met the sea, compacted over millennia into the soft ground that every campanile and palazzo here has had to be driven into on timber piles. It is the reason the city tilts and settles the way it does, and the quiet, invisible fact behind every bridge you have just crossed.