It is a tragic day in St. Louis as the founder of the City Museum and Turtle Park is found dead at the site of his latest project. Bob Cassilly, 61, was found dead inside a bulldozer at Cementland in north St. Louis at the intersection of Riverview and Scranton.

Cassilly had been working on Cementland for ten years. It's an old cement factory on about 50 acres that Cassilly was looking to turn into an attraction.

Investigators say they got a call for a man found dead inside a tractor around 8:00am Monday. Cassilly was apparently found by a co-worker.

Cassilly's close friend Bruce Gerrie says Cassilly was working at Cementland Sunday when the bulldozer he was in rolled over.

Cassilly was apparently working on making a road on a hill when the ground gave way and the tractor rolled three times.

Gerrie says Cassilly was not wearing a seatbelt.

We're told red flags started going up when Cassilly did not pick up his 5-year-old son and brother Sunday.

Cassilly was found Monday morning still inside the bulldozer.

Several agencies including OSHA are now investigating.

Gerrie says Cassilly was trying to open Cementland as soon as possible.

Now many people are mourning his tragic and sudden death.

Cassilly is best known for founding the City Museum. Cassilly is known as a sculptor and entrepreneur. His works also include sculptures in Turtle Park near Hampton Avenue, hippos for a playground in Riverside Park in Manhattan, several sculptures in the St. Louis Zoo, a large butterfly sculpture near the Butterfly House, and many more.

In 2005, the Project for Public Spaces listed the City Museum among the "Great Public Places in the World."

Cassilly got his masters from Fontbonne University in St. Louis.

A remembrance page has been set up on Facebook for Bob Cassilly

List of some of Cassilly's works around St. Louis from the Regional Arts Commssion: Cassilly Sculptures