Largest cooling towers:
Cooling towers are heat removal devices used to transfer process waste heat to the atmosphere. These cooling towers are found at really big dimensions at most power plants. The primary use of large, industrial cooling towers is to remove the heat absorbed in the circulating cooling water systems used in power plants. These things have to be so big to be able to cool the water in a constant rate. If these things are not used you need an enormeous amount of cooling canals which for example can be seen at the Turkey point power plant in Florida.
The world's tallest cooling tower is the 200 meter tall cooling tower of Niederaussem Power Station in Germany. The skyline of the villages nearby are all dominated by this thing:
The cooling towers of the Belleville nuclear power plant in Billeville sur Loire in France are also giants. These cooling towers are 150 meters in diameter at the base, and are about 170 meters high:
These things were climbed by Greenpeace activists in 2007 as you can see in the pictures below. This way you can easily estimate how big these structures are:
Even the open structure at the base is taller then you would think:
Other huge cooling towers can be seen (not yet visible in google maps) at the new expansion of the Neurath Power station in Germany which was recently completed. The 2 cooling towers here are each 170 meters tall:
The cooling towers during construction: