4. The Lost Synagogues of New York City

Untapped Cities reader Ellen Levitt has written three books on the city’s “lost synagogues.” One focuses on Queens, another on Brooklyn, and the last on Manhattan. Each book features photos of over eighty buildings that were once synagogues. Levitt also researched each of these buildings and tells their histories, comparing what they once were to how they are now. In addition, Levitt maintains a Facebook page that she continually updates with photos of lost synagogues, each with a short caption summarizing its story.

In other quirky projects, there’s the ongoing quest to break the Guiness World Records for riding through every subway station.