Mapping NYC's historic landmarks

For 52 years, the New York City Landmarks Preservation Commission has worked to protect the city’s rich architectural and cultural heritage by designating historic districts and individual, scenic and interior landmarks. Through an update to the LPC’s interactive map, Discover NYC Landmarks, users will be able to view detailed information on nearly 34,000 historic buildings within the city’s 141 historic districts.

Daniel Watts, LPC’s GIS administrator and planning analyst, worked with a team of four graduate students to translate data from the city’s landmark designation reports into a searchable tool that filters buildings based on construction date, architect, style, building type and original use.

As a starting point, the team used a dataset from the city’s Department of Buildings to determine the boundaries for the historical landmarks and then incorporated information from tax lot data and building footprints to provide additional context. The team spent a year working through all of the data and designation reports to build the largest and most comprehensive historic building dataset created by any municipal preservation agency in the United States.

“We had to essentially survey 52 years of designation reports to figure out a database design that would be flexible enough to [accommodate] a range of different styles, presentations and information,” Watts told GCN.

Filters were added to the interactive map based on how the LPC traditionally portrayed information in data reports. Reports from the 1960s were one-page-documents with a building description and designation information.

Today's reports are more detailed, with pages of information on architectural details, alterations, site history and photos. Map users can search for details such as a Greek revival architectural style, but details from more recent reports let users search for alterations, restorations and time period. The map is designed to be updated weekly when new landmarks are made official.

For those exploring on the streets of New York City, a mobile version of the interactive map can help users find landmarks near them and offer details they might otherwise miss.

The LPC chose Esri’s ArcGIS platform for its flexibility and ease of use. Watts used the platform to create story maps tied to the 150th anniversary of the LGBT pride month and 100th anniversary of the women’s suffrage movement.

“As we’ve grown more comfortable with the ins and outs of the platform, it can become very appealing for us as a small agency,” Watts said.

Prior to the release of the interactive map, information about the buildings in historic districts was available, but as scanned documents that could not be easily searched, compared or analyzed.

"[Now], with just a click of a mouse, users can learn a building’s age, architect, style, type and more,” said Lisa Kersavage, LPC director of special projects and strategic planning. “The result is a highly accessible, robust and detailed set of information that can be easily searched and compared, allowing for a greater understanding of the city’s historic district buildings.”