This interactive map shows the story behind every landmarked building in NYC

This month marks the 55th Anniversary of the New York City Landmarks Preservation Commission, and to celebrate the occasion, it's created a cool new online feature that details its vital role in saving NYC's architectural heritage for posterity. The site provides a timeline of landmark designations, as well as an interactive map that allows searches by address or building type.

The creation of the Commission grew out of a trend that marked development in New York after World War II. From the end of the 1940s to the middle of the 1960s, the city waged a massive campaign of urban renewal (aka slum clearance). Spearheaded by New York's autocratic Parks Commissioner, Robert Moses, the program aimed to remake Gotham into a web of superhighways, with high-rise buildings isolated on so-called super blocks that deviated from NYC's grid plan. Entire neighborhoods were torn down to make way for projects like Stuyvesant Town and Lincoln Center, while expressways were plowed through otherwise vibrant sections of Brooklyn, Queens and the Bronx.

This feverish re-building finally produced a backlash with the destruction of the old Pennsylvania Station in 1963, which was leveled to make way for Madison Square and the adjacent 1 Penn Plaza tower. Opened in 1910, Penn Station was designed by McKim, Mead & White, and was considered the epitome of Gilded-Age, beaux arts architecture. It welcomed travelers into an soaring main waiting filled with arches and Corinthian columns inspired by the Baths of Diocletian in Ancient Rome. Its demolition was seen as a travesty and marked the moment New Yorkers began to rethink the efficacy of destroying the past in the name of the future. In 1965, Mayor Robert Wagner, signed the law that created the commission. Without it, places like Grand Central and Soho's cast-iron district might have faced the wrecking ball.

You can check out more of the Commission's work on its anniversary website to see just how much of New York as we know it could have vanish—and thankfully didn’t. Find the timeline here, and the interactive map here.