The Inco Superstack is the tallest chimney in the Western hemisphere. Wikipedia says:

The Superstack sits atop the largest nickel smelting operation in the world at Inco’s Copper Cliff processing facility in the city of Greater Sudbury. It was constructed by Inco Limited in 1972 at an estimated cost of 25 million dollars. The 1,257 foot (381 m) structure was built to disperse sulphur gases and other by-products of the smelting process away from the city itself. As a result, these gases can be detected in the atmosphere around Greater Sudbury in a 150 mile radius of the Inco plant.

150 miles doesn’t seem all that surprising when you see the vast plume of fumes extending Northwards.

Thanks: Ian

You can never find a taxi when you need one and at JFK airport that’s because they’re all hiding in a four acre sea of yellow known as the Central Taxi Hold. According to the New York Times the drivers wait here for up to five hours at a time, playing football, dominoes or backgammon. Apparently it’s worth the wait though as the drivers earn a $45 flat fare to Manhattan.

Thanks: Jon Abad

Very close to each other near Walnut Grove CA, are three utterly enormous communication towers. Firstly is the Channel 40 Tower which stands at 608.7 metres, then just a little South is the Hearst-Argyle Tower which stands at 609.6 metres (there’s actually 17 communication towers in the US at exactly 609.6 metres, presumably they’re all just the same kind?).

Finally we have the KXTV/KOVR Tower, an absolute behemoth of communications towers. Standing at 624.5 m the structure is taller than the CN Tower, and officially the 3rd largest structure in existence (the first two aren’t covered by hi-res images on Google yet). There’s loads more of these towers across the US, but they all start to look kind of the same after a while…

Thanks to Josh Kaplan.