Lisbon faces an estuary, not a river. Where the Tagus meets the city it widens into the Mar da Palha, the Sea of Straw, some 14 kilometres across, then narrows to a channel barely two kilometres wide before the Atlantic. That geometry is why Lisbon Boat Tour Sunset tours exist at all: the water runs west, the sun sets downstream, and the city's seven hills catch the last light from across the deck. The waterfront those boats leave from is a reconstruction. The earthquake and tsunami of 1 November 1755 flattened the Ribeira Palace and the shipyards beside it; the Marquês de Pombal rebuilt the riverbank on a grid, and Praça do Comércio replaced the royal court with arcades and a customs house. Cais da Ribeira das Naus keeps the older name — the naus were the carracks careened on this shore during the sixteenth century, bound for Goa, Malacca and Nagasaki. Downstream, Doca do Bom Sucesso sits below Belém, where the Torre de Belém was completed around 1519 to Francisco de Arruda's design and listed by UNESCO in 1983. Seen from the deck, the architecture resolves into a single line. The 25 de Abril Bridge, opened in 1966 and renamed after the 1974 revolution, carries 2,277 metres of suspended roadway and a railway deck added in 1999. Across the channel in Almada, Cristo Rei has stood 110 metres above the south bank since 1959. Between them, the Padrão dos Descobrimentos points its prow at the water, and behind it the limestone of Alfama turns the colour of brass for roughly twenty minutes. Lisbon sits at 38.7 degrees north, which gives it long, slow dusks — the reason a Tagus River sunset cruise reads differently here than on a lake. Tidal range reaches about four metres, so the river moves under the hull with real force, and the light arrives twice: once directly, once off the surface. A cruzeiro ao pôr do sol no Tejo therefore functions less as sightseeing than as a change of vantage; the azulejo façades, the cranes of the old docks and the Vasco da Gama Bridge further east all read as one continuous elevation. A Lisbon Boat Tour Sunset tour is, in effect, the city's own front elevation seen the way it was designed to be seen — from the water, approaching.