It's not every day the world's richest man trades a mansion for a metal box. Yet Elon Musk-worth hundreds of billions and famous for reshaping industries-now calls a 375-square-foot prefab house home.

Hyderabad House in central Delhi, once commissioned by the world’s richest man, has evolved from a princely palace into a ...

A hundred years ago, America's wealth concentrated in New York's Fifth Avenue. Today, the richest Americans reside in places ...