Princeton University Library has a rich collection of print and digital maps. The majority of the print collection is housed at the Map and Geospatial Information Center located in the Lewis Library’s Fine Hall Wing, but you will also find maps in Special Collections and digitally at maps.princeton.edu. You may also want to consult with Wangyal Tsering Shawa, PUL's GIS and Map Librarian.
The best place to start your search for maps is the PUL Catalog. For example, if you are interested in maps of Calcutta, you can simply put that city name into the search bar and use the facets on the left to narrow down, e.g. Under Format, select Map. Then, you may choose to narrow down even further by limiting the publication year or selecting Special Collections under Library. You may also want to explore atlases of South Asia by searching: atlas AND "South Asia". See also, "A handbook for travellers in India, Burma, and Ceylon."
For digital maps, check out maps.princeton.edu. This portal contains digitized maps held by Princeton and other institutions. You can start by searching for location name, e.g. Calcutta, then narrow down by year, and sort by year.
Outside of Princeton, you may also want to explore the maps and atlases hosted by the Digital South Asia Library. See in particular: