The Visionary Mega-Tower That San Francisco Never Built

Back in 1991, architect Eugene Tssui designed a tower that would put all other modern skyscrapers to shame. At a mile wide and two miles tall, plans for the Ultima far surpassed the height of any artificial structure the world had ever seen. More importantly, its design promised to solve many of the complicated issues plaguing urban areas.

The concept for the Ultima began as part of a contracted study of the San Francisco Bay area, during which Tssui and his team were struck by how few park-like spaces the city had to offer. In an effort to minimize urban sprawl and preserve what natural spaces were left, Tssui designed a vertical structure modeled after African termite mounds—the tallest structures not made by man—which can reach up to 30 feet in height. The end goal, Tsui says, was an ambitious one: to make San Francisco “a benchmark for ecologic living for the entire planet.”