Just think, something that tall is gonna have a concrete pier/footing that is as deep as it is tall.

And another thing average people don't understand, is commercial or heavy use concrete has to cure for weeks. What this means is the concrete has to be kept at a certain temperature for a few weeks in order to get the required strength. Often times, especially in the summer, after the concrete is hard enough, crews will put a water sprinkler system on the concrete and cover wet burlap blankets on top to help keep the concrete cool. I've worked on bridges where we tapped right into a fire hydrant, and ran water continuously for 14 days, in order to keep the bridge deck cool. That was one bridge. About a quarter mile long, and 100' long, pretty average bridge.