Cortlandt Alley

Looking for something off-the-beaten-path to do this Halloweekend? Mmuseumm might be right up your alley. And speaking of alleys, it's located on Cortland Alley in Chinatown within a single, abandoned elevator shaft. The 60-square-foot Mmuseumm is a modern natural history museum that exhibits contemporary artifacts, illustrating "the complexities of the modern world." Its eclectic collection of everyday items includes toothpaste tubes from around the world and papers left behind in copy machines.  It even manages to fit a gift shop and café in its tiny footprint.
More info on the museum here