The Vanderbilts were once the wealthiest family in America. Cornelius Vanderbilt was the richest American until his death in 1877. After that, his son William acquired his father's fortune, and was the richest American until his death in 1885. The Vanderbilts' prominence lasted until the mid-20th century, when the family's 10 great Fifth Avenue mansions were torn down, and most other Vanderbilt houses were sold or turned into museums in what has been referred to as the "Fall of the House of Vanderbilt".