Discover Colonna di San Marco e San Teodoro

Both shafts are single pieces of stone rather than drums stacked and pinned -- monolithic granite, quarried in the eastern Mediterranean and shipped whole. That is the hard part: a monolith cannot be assembled in place, so the entire length has to be moved, landed, and then pivoted upright in one operation.

Nicolò Barattieri's method around 1172 is recorded only loosely, but the principle was to raise each shaft on soaked hemp ropes that shortened as they dried, walking the column upright by degrees rather than lifting it. A third column is said to have been lost in the lagoon during unloading and never recovered.

The capitals are the more interesting carving. Both are Venetian work of the 13th century rather than reused antique pieces, and their faces carry trades and crafts, animals and figures -- a low-relief programme meant to be read at close range by people standing beneath them, unlike the statues far above.

The bases sit on a stepped plinth that has been raised more than once as the pavement level of the Piazzetta rose, so the columns stand slightly shorter in proportion today than they did when they went up.