Its not exactly a secret, but not a lot of people know about the 'Ghost Platform' at Sheung Wan's Rumsey Street exit. Apparently in the original plans for the MTR in the early 70s, there was supposed to be a second cross harbor interchange between lines here instead of just the one that now exists at Admiralty. In anticipation of the two line station, they built a portion of a second platform while constructing the island line. It was supposed to connect to a 2nd, cross harbor line. The station wasn't actually completed until 1986 when the island line was extended past Central. Even though they never used it, this short section of platform is still there and accessible since you need to pass through it to get down to the island line if you enter from Rumsey Street's entrance (this is not the main entrance/exit of the Sheung Wan station, but rather a smaller one at the eastern end of the Island line platform).It looks like a very short train platform (apparently only about 3 cars long), except there's no signage and a permanently fixed railing to keep you from falling onto the tracks. Also note that there's no advertisements on the walls, and no sliding glass doors (which OG HKer's know is how all the platforms were before a few years back). I didn't take a picture, but the floor is also bare, no tracks, no ties, etc.At the end of the platform the tunnel is sealed off with cinder blocks. I wonder if they dug the tunnel any further or it stops here. Maybe the bricks are to keep the ghost trains from coming in to the station. :-PYou can read a bit more about it here on the Wikipedia entry for Sheung Wan MTR station.
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