Anytime ground is broken, you never know what will be found below. In the case of a landscaping project, crews stumbled upon the foundation of the San Francisco City Hall that was destroyed during the 1906 earthquake.

The fateful city hall was known for its ever-changing design, which made the total construction project take more than 24 years to complete. The building, once opened, was in use for less than a decade before the Big One struck. The building had been thought to be earthquake proof, but studies later found that the grandiose design lacked any basis in structural integrity.

Workers discovered the ruins beneath the sidewalk in downtown San Francisco. They notified the General Services Administration who dispatched archeologists to investigate the find. The ruins will be studied in hopes they can shed additional light on construction methods that could be use to improve modern buildings. The site will then be re-buried and covered in landscaping.

While the ruins weren’t necessarily lost, their discovery was unexpected.

Read the full story at the San Francisco Chronicle.