Bunkers del Carmel has no bunkers. The concrete rings crowning Turó de la Rovira are open anti-aircraft emplacements, built in 1938 while the city was being bombed from the air, and the guns were gone within a few years. What came next lasted far longer: from the 1940s, families arriving in the city built one-room houses across the summit, a self-made neighbourhood known as Els Canons that stood until the hill was cleared in 1990.
Today the bare concrete is a lookout, and at 262 metres it gives the rare thing in Barcelona: the whole city at once, all the way round. The Eixample resolves into ruled lines, the Sagrada Família's towers stand clear of everything around them, and the wooded ridge of Collserola closes the bowl behind you while the sea fills the rest. Excavation has left the vanished neighbourhood legible, its floor tiles and knee-high wall stubs lying in the grass between the platforms. Late in the day people arrive with bread and wine and sit along the edges until the street lights come on, and the flats on the slope below hear every word.