With the ocean in sight, The Truffle is an unusual vacation home built within a rock. The inhabitable concrete stone is located in Costa de Morte, Spain and was designed by Ensamble Estudio in collaboration with Ricardo Sanz and Javier Cuesta. Its 25 square-meter minimalist decor has everything you’d need for a peaceful getaway, and includes a raised platform bed, modest bath, and built-in fireplace.