Finding old construction permits

We are getting ready to do some minor interior renovations in a condo in the East Village, and have been searching websites, calling 311, poking around the building, to see if earlier construction inside the unit required permits. Super doesn't know. We're planning to reverse the location of a simple, winding wood and iron stairway, which leads to a small sleeping loft, to make better use of the space below. Building is over 100 years old, and the work in the apartment was probably done about 20-30 years ago. Any DOB sites or suggestions to find permit activity? Thanks!