The Tagus estuary at Belém has served as Lisbon's maritime gateway since the Age of Discovery, when Vasco da Gama departed from these docks in 1497 to chart the sea route to India. Today, the Doca do Bom Sucesso remains the principal embarkation point for river voyages that trace the same waterway once navigated by carracks and caravels laden with spices and gold. A Lisbon boat tour Belem reveals the architectural density of Portugal's imperial legacy from a vantage point impossible on land. Belém Tower rises from a limestone outcrop 200 metres offshore, its Manueline battlements and Renaissance loggia designed by Francisco de Arruda in 1519 as both fortress and ceremonial gate. One kilometre east, the Padrão dos Descobrimentos—a 52-metre concrete prow erected in 1960—assembles thirty-three carved figures of navigators, cartographers, and monarchs who financed Portugal's fifteenth- and sixteenth-century expansion. The monument's north face bears Henry the Navigator at its apex, compass in hand, overlooking the river that carried his caravels to Madeira, the Azores, and West Africa. The river itself remains a working estuary. Container ships and fishing trawlers share the channel with tour vessels, maintaining a continuity of function that predates the MAAT—the Museum of Art, Architecture and Technology—whose undulating white canopy, completed in 2016 by Amanda Levete, now anchors the eastern approach to Belém. Passenger routes depart daily between 09:00 and 19:00, with sunset sailings commanding the highest demand in April through October when daylight extends past 20:00. Tagus River cruises from Belém range from one-hour landmark circuits with recorded commentary to three-hour open-bar party voyages featuring live DJs. Smaller sailing craft accommodate twelve to twenty passengers and offer welcome drinks; larger catamarans host up to eighty guests with onboard catering. All routes pass beneath the Ponte 25 de Abril, a 2,277-metre suspension bridge modelled after San Francisco's Golden Gate and completed in 1966, whose rust-red towers frame the Cristo Rei statue on the southern bank. The confluence of sixteenth-century fortifications, twentieth-century engineering, and contemporary museum architecture renders this stretch of the Tagus among Europe's most layered waterfront panoramas.