The Thames Barrier is still prepped for decades defending London against high water.

On Tuesday, the warmest winter day ever recorded in Britain, there was not a cloud in the sky over the Thames Barrier. A tug calmly pulled its barge through one of the channels in the Barrier, which shuts off the Thames when the incoming tide will rise over sixteen feet. This offbeat superdam doesn’t look like anything else: a necklace of giant steampunk silver mussel shells stretched a third of a mile across the river. London began seriously contemplating means of protection after a major dousing in the great North Sea storm of 1953. The Barrier went into operation three decades later. It has decades of usefulness ahead; although climate change was not considered in its design, sea levels along the southern English coast aren’t inching up from geologic causes as fast as originally expected. The Barrier has been shut about 200 times, 50 of them in the 2013/2014 season, when the culprit was not super surges from the ocean but super rain surges that incoming tides would have pumped up further. “It is designed to be bomb-proof and failure-proof,” the Londonist once noted. “When a 3,000-tonne dredger hit the Barrier in 1997, the ship sank. The Barrier lost a ladder.” One of these decades, the enormous wall may be supplemented by a much more enormous dike downstream. In the meantime, “the structure is fundamental to the lives of millions of Londoners,” the London Review of Books commented, “which may be the reason very few of them want to look at it.”