tour odeon larvotto beach

One of the world's largest apartments is going up in one of world's smallest countries. It's a 35,500-square-foot, five-story penthouse being built on a tower in Monaco, a nation of less than a square mile.

The Sky Penthouse will also probably be the most expensive apartment ever built, expected to sell for nearly $400 million.

Related: $25 million homes from around the world

That's not surprising given how wealthy Monaco is -- nearly 30% of its 37,000 inhabitants are millionaires, according to WealthInsight.

Photograph-like artists' renderings above and in the following pages show how the penthouse soars high over Monaco's skyline, providing stunning views from its rooms and terraces.

First published August 25, 2014: 11:42 AM ET

Find Homes For Sale

Mortgage & Savings

LendingTree