Tidal Pools of Leça da Palmeira

Siza was in his late twenties when Matosinhos asked him for a swimming complex on a rocky Atlantic beach a kilometre south of the Boa Nova tea house he had just finished. He built almost nothing that reads as a building. A long concrete retaining wall runs parallel to the coast road and hides the whole installation from traffic; behind it a ramp descends between two blank walls, turns, and delivers the visitor onto the rocks with the ocean suddenly in front. The changing rooms are a dark, low, timber-lined interval on that route. The two tanks are made by adding straight concrete walls to the outcrops that were already there, so that a section drawn through them cannot tell reliably where the geology stops and the construction starts. The pools opened in 1966; work on the complex continued until 1973 and a planned restaurant was never built. Portugal classified them a national monument in 2011.