St. Louis' oldest power plant is a bit north of the Arch. It opened in 1904 and lit all the bulbs in the World's Fair that year. It remained the main source for electricity to downtown for decades, converting in turn from coal to oil to natural gas. It still operates in a limited capacity. It feeds a steam loop throughout downtown so buildings don't need their own boilers. Um, do buildings still need boilers?
Don't see it from the river very often.