Inside St. Paul's chapel, where George Washington prayed after taking the oath of office - that remained standing when the Twin Towers fell across the street

Daniel Brown/Business Insider

St. Paul's Chapel has stood in New York City since 1766.

If you ever find yourself strolling around Manhattan's Financial District, you might miss the small schist and brownstone church tucked in between the towering skyscrapers.

Make sure you don't.

St. Paul's chapel is one of the oldest and most historically significant buildings in the city - in fact, it's the only colonial-era church still standing in Manhattan.

Built in the 18th century, the Georgian Classic-Revival style church has seen a lot.

It's where President George Washington prayed after being sworn in at Federal Hall. It's where President James Monroe's funeral service was held. It's where General Marquis de Lafayette saw the New York Choral Society perform.

It also witnessed and survived the September 11th attacks, serving as a relief center for first responders.

And in honor of the 17th anniversary of the 9/11 attacks, we recently took a tour of the beautiful, old church. See inside: