World's Most Secret Homes

This episode uncovers a 300-year-old Scottish ruin that's been brought back to life by an owner, who had the ingenious insight to build a unique modern home within its crumbling walls. In the Sierra Nevada mountain range, we discover a striking angular home built from zinc and glass to reflect the rugged landscape it sits in. In Sardinia we explore a stunning waterfront villa with its own secluded beach.

A family home in Brazil that is completely hidden in nature; a wartime bunker on the Isle of Wight in the UK that's been tastefully transformed; an ultra-modern home hidden behind a sleek façade in San Francisco.

A modern home commissioned by Lord Rothschild in Buckinghamshire England, built out of flint; a glass residence nestled next to a scenic lake in Switzerland; a treehouse that serves as a dream getaway for a family of five in New York.

From secluded houses in forests to luxury bunkers buried underground, an inside look at some unique homes and their surroundings.

An enchanting villa in the Spanish countryside; an ultra modern cliff-side retreat in the wilds of Switzerland; a cabin that resembles a pair of binoculars perched on a cliff in rural Quebec; a woodland retreat in Portugal.

A futuristic villa built to push the boundaries of architecture on the edge of a lake in Austria; a cabin perched on the edge of a river deep in the forest of Washington State; a unique beachside house built into rock on Formentera.

A palatial clifftop villa complete with indoor and outdoor pools; a remote cliff top home deep in West Virginia; a riverside residence designed to reflect the local wildlife in Suffolk; a retreat built into rocks on the rural outskirts of Stockholm.