In the late 1950s there was a radical idea in Pittsburgh. The Steelers and baseball’s Pirates sought a new stadium, and Eric M. Sirko proposed building the new stadium directly over the Monongahela River.
Based on those two drawings it looked like the proposed stadium was going to be built on a large elevated platform over the river. In the drawing boats were traveling underneath the stadium. The link from the Carnegie Library also states the stadium would have had a 600-room hotel, 100-lane bowling alley, and the world’s largest covered boat dock.
The stadium itself was going to seat 70,000 people, who would have been mostly covered from the rain or snow.
I couldn’t find an estimate on how much the stadium was going to cost. But it was boasted that the stadium would be “self-liquidating”, and because there wasn’t any land involved, there would be no cost in acquiring the site and/or property tax loss.
It’s regrettable the stadium was never built. It probably would have been one of the “Wonders of the World”.