Twenty years ago, Zach and Allison Anderson began digging into a hillside on their property in Grass Valley, California, to escape the heat, cold, and fire risk above ground.

What started as a simple experiment has grown into a labyrinth of domed rooms, tunnels, and courtyards — a cluster of underground homes that now feels like the beginning of an earth-sheltered ecovillage.

Using ferrocement — layers of wire mesh and thin cement plaster that can be molded into almost any shape — Zach has built an affordable way to live underground without the gloom of a bunker or the climate mismatch of an Earthship.

By keeping the insulated living core small and surrounding it with naturally tempered indoor-outdoor rooms, he’s created spaces that stay comfortable year-round while keeping both building costs and property taxes low.

From an underground fishpond to a grotto-turned-living room where parakeets fly freely under a skylit dome, every corner reflects Zach’s inventiveness. Secret bookshelves reveal hidden pantries and stairways; a “living well” — his version of a living wall — channels cool, fragrant air from plants into the heart of the home.

Their most recent build, a compact ferrocement accessory home, may be the most accessible part of the project — a small prototype for anyone dreaming of an affordable, earth-sheltered structure. With just enough space for a Murphy bed and kitchenette, it expands outward into open-air living areas that stay naturally temperate thanks to the surrounding soil.

Zach sees it as proof that underground homes don’t need to be massive or expensive — they can be simple, light-filled, and within reach for anyone willing to dig.