By Vittoria Woodill

PHILADELPHIA (CBS) — The Delaware Valley area is rich with history and one of the oldest relics in the region sits at the end of the one of the runways at Philadelphia International Airport.

Not far from Center City is one of the only forts still in existence that pre-dates the founding of the United States of America — Fort Mifflin in Delaware.

“The fort’s been here for 240 years but because we’re on the outskirts of town, nobody knows about us too much,” Mike Kalichak, a tour guide, said.

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Fort Mifflin is Philadelphia’s hidden treasure. It is soaked in history and in mud. It is also known as Fort Mud Island.

“The ground was always soggy, wet, sometimes. Sometimes the mud was so deep it would suck the shoes off men’s feet,” Kalichak said.

The fort became famous for the siege of Philadelphia during the Philadelphia campaign that occurred on the evening of Nov. 15, 1777.

“We held the British off for six longs week,” Kalichak explained. “We delayed them, otherwise, you know, they could have made it to Valley Forge.”

Fort Mifflin has also been a part of both the Revolutionary War, Civil War, the first and second World War, and it’s right in the backyard of the Philadelphia.

This weekend they will commemorate the 240th anniversary of the siege and bombardment of Fort Mifflin with a full weekend of living history, which means reenactments.