Chiesa di San Zaccaria

San Zaccaria, just behind the waterfront near St. Mark's Square, holds one of Venice's strangest and most atmospheric spaces: a submerged Romanesque crypt where eight early doges lie buried beneath water that rises and falls with the lagoon's own tides.

The nave is free and the crypt, sacristy and choir carry a small combined charge of a few euros. Given that the crypt is a waterlogged 10th-century structure requiring constant attention, this is one of the more obviously well-spent admissions in the city.

The crypt floor is wet, uneven and genuinely slippery, and the duckboards are narrow. It is not suitable for anyone unsteady on their feet, and there is no shame in looking down the stairs rather than going in.

San Zaccaria is an active parish and the neighbouring buildings are a working Carabinieri barracks -- the campo is not a place to picnic, and photographing the convent side rather than the church is unwelcome.

Because it sits so close to San Marco, this is one of the genuinely useful pressure valves in the city: an hour here takes a visitor out of the worst crowding in Venice without moving more than a few hundred metres.

The church itself is free to enter. A small separate fee, around 3 euros, covers the sacristy, the choir stalls, and the flooded crypt -- worth the extra cost for anyone curious about the building's oldest and strangest space. San Zaccaria is a short walk from St. Mark's Square, just behind the waterfront.

The crypt is the reason to time a visit at all. It stands in standing water year-round, and the depth follows the lagoon: at low tide the duckboards sit above a shallow mirror that reflects the columns almost perfectly, while at high water the boards may be under and the crypt closed outright. Checking the tide table is unusually worthwhile here.

Autumn and winter bring the highest water and the best chance of a genuinely flooded crypt -- and the highest chance of finding it shut. Late spring and summer give reliable access and a shallower, calmer reflection.

The church closes for a long midday break, and the ticketed sections -- crypt, sacristy and choir -- keep shorter hours than the nave itself, so arriving late in the afternoon can mean free entry to the church and a locked door to everything worth paying for.

Bellini's altarpiece is a dark painting in a side position and needs either good morning light through the nave windows or the coin lamp; it does not read at all on a grey afternoon.