• Book tickets online ahead, since they often sell out and can't be bought on the day
• The ticket kiosk in front of the monument closes at 4:30pm, half an hour before last entry
• Spiral stairs to the upper floors and terraces, so leave the stroller behind or bring a carrier

Belém Tower is a 16th-century fortress built at the mouth of the Tagus to guard Lisbon's harbor, and a UNESCO World Heritage Site. A walkway leads out to the bastion, where artillery once faced the river and the old storerooms later served as prison cells.

Inside, a spiral staircase climbs past vaulted rooms to terraces with river views. Kids like spotting the stone rhinoceros carved under a turret.