Built to defend the coast, Torre de Belem or Belem Tower resembles a giant beautiful white stone chess piece sitting on the water. Inside there are narrow steps to climb to the top and see if there are any ships approaching to attack the city.
You can either purchase the tickets at the kiosk by the tower or get a skip-the-line ticket online, which is useful with little children. Before entering, explore the intricate carvings on the outside of the tower including remainings of a carved rhino.
There are gardens, restaurants and food carts surrounding the tower and the riverside stretch toward it, which makes it for a lovely walk.
Tickets: €8.50 for adults, FREE for children under 14.
You can reach the tower via E15 tram.