This type of citation creation is called Frankenreference as we have to do the best we can with the information we have on hand.
Date: use (n.d.) as Google maps are created on the fly and not published.
Title: as there is no title describe the map. Enclose your description in brackets.
Retrieval Date: maps tend to change, so it’s a good idea to add a retrieval date along with the maps URL.
Google. (n.d.). [Google Maps, Bank Street College of Education, New York, NY]. Retrieved October 5, 2016, from https://goo.gl/maps/QX9gLFvjsPT2