I've been looking all over the place for the world's tallest structure: a radio mast in North Dakota.
This extremes thing is really cool, by the way. Keep up the good work!
The KVLY-TV mast (formerly the KTHI-TV mast) is a television transmitting tower in North Dakota, USA, used by Fargo station KVLY channel 11. At 2,063 ft (628.8 m), it is currently the world's tallest supported structure on land.