Start at the Liberty Bell. Park rangers are there to interpret the Bell for you. [Free — allow 30 minutes]
Go south a half block and visit Independence Hall, where the Declaration of Independence and the Constitution were born. Adjoining it on the right is Congress Hall where the upper and lower houses of Congress first convened (in the upper and lower floors) , and on its left is Old City Hall, home to the Supreme Court when Philadelphia was the nation's capital. Park rangers are there to answer all your questions. [Free, but requires ticket from Visitor Center — allow 1-1/2 hours]
Walk east along Chestnut Street about 1-1/2 blocks to Carpenters' Hall, where John Adams, Patrick Henry, George Washington, and other delegates formed the First Continental Congress in 1774 — where it all began! Plus, pick up a souvenir of your visit to Philadelphia here. The Carpenters' Company has docents (tour guides) for you. [Free — allow 1/2 hour]
Time for lunch! Go north one block to the Bourse where you will find several restaurants surrounding a court with ample tables. [Not free]
Next stop is the Betsy Ross House. Go north on Fifth one and a half blocks and take a right on Arch Street. Stop briefly at the corner and pay tribute at Benjamin Franklin's grave site then continue two blocks to the shrine to the American flag [Betsy Ross House asks for a voluntary contribution — allow 1/2 hour]
The last stop depends on you.
If you have children, then return to Fifth and across from Ben Franklin's grave is the United States Mint where you can watch coins being minted on weekdays [free — allow 1 hour]
Otherwise, continue east one block, then left on Second Street to visit Elfreth's Alley, the longest continually inhabited street in the original 13 Colonies. [Museum is $1 for adults; 50c for children over 4; free for school groups and children 4 and under — allow 1 hour to see the street and visit the museum]
Eating
Best Ice Cream in Historic Philadelphia...
Franklin Fountain at 116 Market Street, above Front St., 215-627-1899
2 Street Grill 613 S. 2nd Street, 215-627-4864
Adrianne's Bistro 530 South Street, 215-829-9620
Alaska Ice Cream Front & Chestnut Sts., 215-592-8800
Alouette 334 Bainbridge St., 215-629-1126
Alyans 603 S. 4th St., 215-922-3553
Anthony's Philadelphia Old City Pub 226 Market Street, 215-922-1954
Archway Sandwich Shop 53 North 8th Street, 215-923-6106
Artful Dodger Beef & Ale House 400-402 S. 2nd Street, 215-922-7880
Au Bon Pain 201 Market Street, 215-922-8942
Au Fin Palais 120 Market Street, 215-629-9610
Azalea at the Omni 4th & Arch Streets, 215-931-4260
Backstage 614 S. 4th Street, 215-627-9887
Bar B Que House 222 Market Street, 215-922-7223
Barrys Restaurant 215 Chestnut Street, 215-629-0150
Bassett's Original Turkey Gallery Food Court, 9th & Market Streets, 215-574-1690
Beach Club 945 N. Columbus Blvd. Pier 42, 215-829-1900
Benjamin's at the Holiday Inn Independence Mall 4th & Arch Streets, 215-923-8660
Benny's Place 435 Chestnut Street, 215-574-3663
Bistro Below 510 Walnut Street, 215-440-3888
Bistro Romano 120 Lombard Street, 215-925-8880
Blue Moon Jazz Club & Restaurant 4th Street (in Bourse Bldg), 215-413-2272
Bourse Food Court 11 S. 5th Street, 215-625-0300
Brasil's 112 Chestnut Street, 215-413-1700