The Tower of Belém was never really a defensive tower, though it looks like a stronghold. King Manuel I ordered it built in 1514 on a rocky islet near the north bank of the Tagus, as part of a system of fortifications guarding the river mouth and the route to Lisbon, with cannon on the lower platform and living quarters above. Francisco de Arruda, who had worked in Morocco, designed it, and the style mixes Gothic, Moorish and Renaissance touches with the Manueline repertoire of ropes, shields with the Cross of the Order of Christ, and stone sails. A tiny stone rhinoceros under one of the turrets is often described as the first European sculpture of the animal, a creature that had arrived in Lisbon in 1515 as a gift for the Pope, and which Dürer famously drew from a description.
The Tagus has changed its course since then. Over the centuries the riverbank has shifted and silt has built up, so the tower, which once stood in the water, is now joined to the shore by a short walkway. The earthquake of 1755, which devastated much of Lisbon, damaged it but spared much of the stonework, and it was a prison for a time, then restored in the nineteenth century. UNESCO listed it with the Jerónimos Monastery in 1983.
To go inside means to climb narrow spiral staircases, and queues can be long in summer, so go early. The terrace on top offers a view over the river, with ships heading out beneath the great bridge. It is a good place to watch the light on the water, and especially lovely in the late afternoon, when the stone turns golden.
On a motorcycle, the riverside is simple, with a wide road, plenty of parking and views of the water, though wind off the Atlantic can be strong. The ride list heads north to Mafra, where a monumental baroque palace and monastery built with Brazilian gold fills a vast front of white stone, an hour's ride through Lisbon's outskirts and then the rolling farmland of the Estremadura. Fuel is plentiful on the way, and Algés, a short distance upriver, has stations on the main road.
Try the grilled sardines of summer in a nearby tasca, and keep your helmet for the bike.