We had a tank you could play in in our city park (mt. Carmel, IL) when I was growing up (the 80s and early 90s). It was open and you could climb underneath and in, or in through the top, all the moving parts were welded shut. In the late 90s, they welded the doors shut, and now I think its gone. It was a ton of fun playing in that thing though.
(Cornier Than Ethanol, XL, Serene Green)
(Lawn Gegnome Project, XL Military green)