The Nieuwe Hollandse Waterlinie was a strategic defense area from the 1800s to the 1960s. Located in the Netherlands’ west, the low-lying land was engineered with canals and sluices that could flood the area with a layer of water deep enough to make travel by foot dangerous yet shallow enough to prevent boat access.

In 2004, the country enacted a plan to recast the zone for contemporary use while also nodding to its historic significance. Enter architect Bruno Despierre of Brussels-based firm B-ILD. He won a commission from Famous, an advertising agency, to morph a 140-square-foot underground bunker built by the Dutch government in the first half of the 20th century into a holiday home.

To accommodate four people in the compact space, Despierre deftly devised a fleet of built-in multipurpose furniture pieces, all made from meranti-finished plywood. A table and cabinets disappear behind sliding panels; bunk beds fold discreetly against the walls; stools serve as nightstands, as steps to access top bunks, or as seats at the dining table. “Since it’s limited in space, we designed an interior that is as functional as possible and doesn’t leave a square inch unused,” he says.