As seen on... Roosevelt Island

The ruin of the smallpox hospital at the tip of Roosevelt Island is one of my favorite 'urban decay' landmarks in NYC.
Known as "The Renwick Ruin", it was built by James Renwick in the 1850's to serve the victims of the smallpox epidemic that was sweeping the country in the days of the Civil War.
Renwick was famous for his Gothic Revival structures, of which more than a few have been designated as NYC landmarks. These include; Grace Church, St. Patrick's Cathedral, and the Greyston Conference Center in the Bronx.
I love biking to the tip of Roosevelt Island. You can take a bike over on the tram from 60th street in Manhattan, but it's much more satisfying to use pedal power and come across the connecting bridge from Astoria at Vernon Blvd. and 36th Ave.
It's one of those great hidden places where you are at the center of it all and yet, are almost always alone. From East to West, there are spectacular views of LIC, the Williamsburg Bridge, the UN, and Sutton Place.
The view of the ruin, glowing eerily on the shore of the island, has mesmerized many a New Yorker over the years. I've always been jealous of those who have been inside - but not jealous enough to jump the fence.

For more info on the ruin go to The Roosevelt Island Historical Society.