There’s an element of the primitive in this spartan refuge located on Vieques, a remote island off the coast of Puerto Rico, where wild horses roam the countryside, and the land itself feels far removed from the encroachment of the modern world. The client was looking for a place to disconnect from their professional life and the chaotic pace of the city. The firm devised a no-fuss encampment that hugs its hillside site and opens onto dazzling views of the Caribbean Sea. Habitable only in warm, mild weather, the house is designed as a modular composition of concrete planes and volumes inspired by the concrete bunkers of an abandoned U.S. military base on Vieques, with no glass whatsoever. The individual volumes can be opened and closed quickly and easily via folding walls of ipe wood panels. These hard-wearing rooms distill the concept of domesticity to its most simple form, offering a visceral connection between interior space and the land surrounding it. The upper volume accommodates the primary bedroom, an adjacent outdoor tub and shower, and an open living area that cantilevers above the narrow lap pool that connects the main house to a small guest casita. This raised structure affords the clearest views of the Caribbean. Below the living container, an outdoor kitchen can be secured by another set of wooden shutters. A walled garden separates the main house and the guest pavilion. Although essentially indestructible, the concrete material will eventually accrue patina and age in response to the forces of wind, sun, air, and rain. This elemental sanctuary represents the vision of a modern castle—a fortified redoubt from the hurly-burly of modern society, complete with a reinterpreted moat.