Philadelphia is known as the birthplace of the United States, the nation's cradle of liberty. It began back in 1776 when the 13 American colonies announced their independence from the British Empire with their Declaration of Independence. And Philadelphians, along with other Americans, mark this day of freedom every July 4th. As the nation prepares for its 233rd birthday.

The first stop for many tourists to Philadelphia, Pennsylvania is Independence Hall -- the place where the founding fathers met to discuss and write the Declaration of Independence.

Bill Caughlin"People want to come to see the birthplace of the United States," Bill Caughlin said. Caughlin is a ranger with the National Park Service. "This is it. It all starts right here (in Philadelphia). I think what attracts people the most is the fact that we are a nation that is founded on ideals, on equality and freedom. And I think that attracts a lot of people from around the world. They want to come and see that room where that Declaration of Independence came out of."

And those ideals are memorialized not just in that declaration, but also elsewhere along Independence Mall. Actors dressed as key early American patriots -- George Washington, Ben Franklin -- add to the historic ambience, and talk to tourists. Famous relics and sites such as the Liberty Bell, Carpenters' Hall, and the house where legends says seamstress Betsy Ross sewed the first American flag attract more than three million visitors to Philadelphia each year.

Liberty bellThe Liberty Bell was rung on July 8th, 1776 to summon Philadelphians to hear the first public reading of the Declaration of Independence. In 1846, after a tiny crack expanded to the point that the bell could not be rung, it was removed from the Independence Hall tower and put on display.

"It's such a powerful symbol, really, I see that on a regular basis. The bell, by the time it did crack, was already an important relic from the time of independence," Caughlin explains. "But also would become a symbol of freedom for people in the United States, pretty soon around the world."

And more people from the United States and around the world visit Philadelphia for the 4th of July holiday than at any other time of the year.

"July 4th is our time to shine here!" Caughlin proudly proclaims.