Walk along the beachfront between Embaré and José Menino and you will start to notice that many of the high-rise apartment blocks lean. Several of them lean dramatically. The cause is the sand-and-clay soil beneath: when the buildings were thrown up in the 1950s and 60s, foundations were not always sunk deep enough, and the towers settled unevenly as the substrate compressed.
About 100 buildings have measurable tilts. Some have been quietly straightened by hydraulic engineering; others remain as they are. It is an odd, photogenic detail of the seafront skyline, especially as the late-afternoon light picks out the discrepancies between balcony lines on neighbouring towers.