Bob Cassilly, 61, was killed this morning in a bulldozing accident. The famous sculptor, best known as the founder of the St. Louis City Museum, was found at Cementland, his latest industrial art project, after he failed to show up for a scheduled appointment.

Cementland, a still-unfinished site along the north St. Louis riverfront, was a decade-long project for Cassilly. Once a 54-acre cement factory, it was repurposed in 2000, and has since become home to a castle, numerous tunnels, and sculptures made of old cement-makers and airplane fuselines. Cassilly frequently operated the bulldozers on site, and appears to have been trapped under one of the vehicles when it overturned.