The city transforms itself over and over in time. For the city of New York now it is possible to follow some of these changes:
Urban Reviewer is a comprehensive online map showing all the renewal plans for New York City. Additionally you can move the time slider in order to see the concentrated areas of urban renewal depending on the time it is adopted. The project team, 596 Acres, states that this project took two years to follow up on a Freedom of Information Law request for records of those plans and meticulous translation of paper plans into machine-readable spreadsheets to make the map.
These plans have existed in paper form in public renewal offices, but have been inaccessible to the public, until now.