The Jerónimos Monastery, on UNESCO's list since 1983 with the Belém Tower down the shore, has its cloister as the reason to come. Two storeys of stone tracery run around a square courtyard, and almost no two arches are carved alike, so an hour spent walking it slowly is the right way to use the building. In the church, columns rise like palms and fan into a single vault so wide it has no visible support at the centre. That vault stood through the earthquake of 1755 while most of the lower city fell.
Ropes, knots, coral, sea monsters and armillary spheres are carved all over the pale Lioz limestone, so the economy that paid for the monastery is spelled out across its walls. Manuel I ordered it in 1501 and paid for it with the vintena da pimenta, a five per cent duty on commerce from Africa and the East. It stands where Vasco da Gama and his crew spent the night before sailing in 1497, and he lies in a tomb inside the west door, opposite the poet Camões. Both tombs were installed in the nineteenth century, and whose bones are in them is doubted.