There’s no denying that curves and blobs have been the dominant silhouettes of the design scene this decade, but lately we’ve seen the trend taken to the extreme—in the form of whole rooms and buildings rendered in undulations. Cases in point: the Gilder Center, the delightfully amorphous new addition to the Museum of Natural History in New York City (see image below); Robert Downey Jr.’s eco-conscious Binishell house in Malibu (go here for a peek); and the otherworldly Italian vacation home of Francesca Amfitheatrof, the artistic director of jewelery and watches at Louis Vuitton (you can see it here).

Besides bulbous contours and sinuous lines, what these projects have in common is their resemblance to cave dwellings. This type of architecture is most commonly found in the Mediterranean countries, but more and more the cave aesthetic—plastered or concrete walls, soft curves, built-in nooks and crannies—is being replicated in other parts of the world, even in cities.

Below, we’ve rounded up some standout examples, followed by practical iterations of the trend for the homeowner who wants to just dip a toe.

Big Curves