Curious about the past, take a look at the NYC Photo archives in the links below
You can either type in an address once you open the link (with zip code) , or you can “walk” the site, moving your cursor to wherever in the 5 boroughs you want to go, then go to a dot and click on it, for example. This way you can view an entire street, or neighborhood, at will.
The map shows the “footprint” of buildings that are at the address today, so you are able to view buildings that no longer exist, but that were there in 1940. Sometimes photos are missing, or badly damaged and unreadable. Some are bad photos, or blocked by foliage, so there can be disappointments.
Please be advised that, like the archive these were taken from, the buildings are not always in the right place. But they are usually close. So sometimes you may click on an address only to find the wrong house. If that happens, click the dots nearby and you may find the building you are looking for!