Any tour of Philadelphia should start with Independence National Historic Park, or INHP, "America's most historic square mile", which covers a mere¹ four blocks just west of the Delaware River between Walnut² and Arch, but can take more than a day to explore in full. The solid red-brick buildings here, not all of which are open to the public, epitomize the Georgian (and after the Revolution, Federalist) obsession³ with balance and symmetry.

All INHP sites (unless otherwise specified) are open 365 days a year and admission is free; hours are usually 9am to 5pm, sometimes longer in summer. The visitor center at Third and Chestnut⁴ (daily 9am–5pm, open until 6pm July & Aug; 215/597-8974) has maps and shows a short, somewhat ghostly film, Independence, directed by John Huston. Free tours set off from the rear of the east wing of Independence Hall, the single most important site.

It's best to reach Independence Hall early, to avoid the hordes⁵ of tourists and school parties. Built in 1732 as the Pennsylvania State House, this was where the Declaration of Independence was prepared and signed and, after the pealing⁶ of the Liberty Bell, given its first public reading on July 8, 1776. Today, in the room in which Jefferson et al drafted and signed the United States Constitution, you can see George Washington's high-backed chair with the half-sun on the back – Franklin, in optimistic spirit, called it "the rising sun".

The Liberty Bell itself hung in Independence Hall from 1753, ringing to herald⁷ vital announcements such as victories and defeats in the Revolutionary War. Stories as to how it received its famous crack vary; one tells that it occurred while tolling⁸ the funeral of Chief Justice Marshall in 1835. Whatever the truth, it rang publicly for the very last time on George Washington's birthday in 1846.

Later in the century, the bell's inscription⁹ from Leviticus, advocating liberty "throughout all the land unto all the inhabitants", made it an anti-slavery symbol for the New England abolitionists – the first to call it the Liberty Bell. After the Civil War the silent bell was adopted as a symbol of reconciliation¹⁰ and embarked¹¹ on a national rail tour. The well-traveled and somewhat lumpen icon¹² now rests at eye level in a purpose-built concrete-and-glass pavilion on Market Street between Fifth and Sixth.

Next door to Independence Hall on Sixth and Chestnut, Congress Hall, built in 1787 as the Philadelphia county courthouse, is where members of the new United States Congress first took their places, and where all the patterns for today's government were established. The US Supreme¹³ Court sat from 1791 until 1800 in Old City Hall, on the other side of Independence Hall on Fifth and Chestnut.

In 1774, delegates of the first Continental¹⁴ Congress – predecessor¹⁵ of the US Congress – chose defiantly¹⁶ to meet at Carpenter's Hall, 320 Chestnut St, rather than the more commodious¹⁷ State House, to air their grievances¹⁸ against the English king. Today the building exhibits early tools and furniture (Tues–Sun 10am–4pm). Directly north, Franklin Court, 313 Market St, is a tribute, on the site of his home, to Benjamin Franklin. The house no longer stands, but steel frames outline the original structure. An underground museum has dial-a-quote recordings¹⁹ of his pithy²⁰ sayings and the musings of his contemporaries, and there's a working printshop. The B Free Franklin Post Office, 316 Market St, sells stamps and includes a small postal²¹ museum. Other buildings in the park include the Philosophical²² Hall, 104 S Fifth St, still used today by the nation's first philosophical debating society (founded by Franklin). The building is closed to the public, but features a statue of Ben in intellectual mode, garbed²³ in a fetching toga. The original Free Quaker Meeting House, two blocks north of Market at Fifth and Arch, was built in 1783 by the small group of Quakers who actually fought in the Revolutionary War.