At 87.5 feet above street level, the Smith-9th Streets station, served by the F and G trains, is the highest subway station in the world, according to the MTA. (191st Street in Upper Manhattan, on the 1 line, is the city's deepest station, 180 feet below ground.)
From June 2011 until April 2013, Smith-9th was closed while it was being renovated (by a team of space aliens, it would appear). The station is open and functional now, but work on the exterior continues, as you can see.
UPDATE: The renovations are complete! Here's a look at the finished station.