São Jorge Castle
Start where Lisbon itself started. People lived on this hill at least as early as the 8th century BC, and its strategic value never faded: Celtic tribes used it first, then Phoenicians, Greeks and Carthaginians held it as a defensive outpost, and after them came Romans, Suebi, Visigoths and Moors. The first real fortification probably went up around 48 BC, when Lisbon was classed as a Roman municipality.
The walls you walk along today go back to the Moors, who built them in the 10th century as the Cerca Moura, the Moorish Encirclement. In 1147 Afonso Henriques took castle and city with northern European knights who were on the Second Crusade; it became the only notable success of that otherwise failed crusade. The siege has its own legend, retold ever since: the knight Martim Moniz saw a castle door standing open and threw his own body into the gap so the defenders couldn't shut it, letting the Christian soldiers in at the cost of his life.
After the conquest the castle kept changing roles: royal palace, military barracks, home of the Torre do Tombo national archive, and now a national monument and museum. The castle charges admission, with reductions for young visitors and seniors and free entry for children. It's worth it if you want to walk the Moorish walls and understand where the city began; give it about an hour and a half.
The castle opens early every day, which makes it a natural first stop before you head down into the city.
From the castle comes the longest leg of the day: 1350 m, about 19 minutes, down through Alfama into the lower town to the Santa Justa Elevator.
