Didn't know there was a basement?

A photo posted by Geneviève L'Heureux (@genlhx) on

The ruins of a once-populous building at the corner of 22nd and Mission has been plagued with problems since it was the site of a fatal fire in January of last year. It has caught afire at least three more times, is full of rats, and its owner has been slapped with a lawsuit by 48 of its former tenants. And yesterday, area residents report, it was the site of yet another mess, when a construction vehicle that was supposed to be dismantling the disaster zone accidentally fell through the floor of the once-bustling structure.

Looking at the photos posted by Geneviève L'Heureux (embedded above and below) the CAT excavator was working at street level when it smashed through the ground floor and into, perhaps, the structure's basement.

According to CAT's website, excavators similar to this fallen one range between 18,517 and 88,800 pounds in weight.

The demolition effort has been months in the works, following a February 19 emergency order from San Francisco's Department of Building Inspection ordering owners to demolish what was left of the building. Described by Mission Local as "a symbol of landlord negligence," the many issues at the site have inspired legislation tightening rules around smoke detectors in residential buildings and "requiring that landlords keep the city informed of safety standards within their buildings."

A photo posted by Geneviève L'Heureux (@genlhx) on