The New York Public Library’s OldNYC site allows you to explore via a map, it’s collection of historic photos of New York City.
Find an interesting location on the map, and then try to place that image overlapping a current view of the location from Google Street View:
The corner of 7th Avenue and 26th Street, then and now; I think the horses pulling that cart want a Chipotle Barbacoa Burrito
This view of the OldNYC map put into today’s Google Streetview
Tweet your response to @ds106dc and be sure to include the hashtag #tdc1677
Don't Want to Tweet Your Response? Really?