Belém Tower, a UNESCO World Heritage site, is a historic fort on the Tagus River, symbolizing Portugal's Age of Discoveries. While generally accessible, some areas may pose challenges for visitors with mobility issues due to narrow passages and stairs. Solo exploration is feasible, though guided tours offer richer historical context. Expect crowds, especially during peak tourist season (summer). The cost to enter is typically around €6-€8, and a visit usually lasts 1-2 hours. Be prepared for potential lines and consider purchasing tickets online in advance. Note that the tower can be closed on certain public holidays or for special events.