The New York Public Library (NYPL) has developed an open-access tool called MapWarper, which allows users to rectify historical maps from its collections and make them available to the public. The library's developer team has created over 10,000 maps that can be used for various purposes. NYPL's basemap importer makes it easy to borrow these historical maps for use in CartoDB projects. Users can access MapWarper by clicking "Select basemap" in their CartoDB Editor and inputting the URL of a supported historical map. Once the map is added, users can annotate and add features such as points and lines. The NYPL's "Mapping the Past" feature series will share cool historical stories using CartoDB, providing users with opportunities to explore the past through interactive maps.