08/08/2025
Millennium Tower, a luxury high-rise in San Francisco, has become infamous for an engineering flaw that caused it to sink and tilt since its completion in 2009. Located in the heart of downtown, this 58-story residential skyscraper was marketed as one of the city's most prestigious addresses. However, over the years, residents noticed alarming signs — cracks in walls, uneven flooring, and doors that no longer closed properly. By 2023, the building had sunk approximately 18 inches into the ground and leaned more than 30 inches to the northwest.
The primary cause of the issue lies in the tower's foundation, which rests on a concrete slab supported by friction piles embedded into dense sand, rather than deeper bedrock. This design choice, though cost-effective at the time, proved risky in San Francisco’s soft soil. A \$100 million retrofit project involving steel piles driven to bedrock was launched to halt further tilting and restore public confidence.
