We're history geeks in our family so, for us, Philadelphia is our Walt Disney World. All that walkable history in one place? Heaven!
And, though there is plenty to do and see beyond the historical sites, if you're making the long trip (it is about a 500-mile drive from central Ohio), it is probably best to build a visit around the history (watch the cult-classic movie musical 1776 beforehand, not for factual accuracy, but to get in the spirit … of '76!).
You could fly to Philadelphia from Port Columbus (round-trip fares are in the $250-$325 range), but driving the I-70 to Pennsylvania Turnpike (I-76) route gives you the option of visiting other sites like Valley Forge, Gettysburg and the Flight 93 National Memorial in western Pennsylvania.
Driving within Philadelphia, though - well, how do I put this? Try not to. Get yourself safely to a downtown hotel and leave the car there (on our last trip we stayed at the Sheraton Philadelphia Society Hill (1 Dock St.); which was perfectly situated for walking and public transiting; hotels along the Delaware River in the Penn's Landing neighborhood also are close to the historical action). The city streets are narrow and often cobbled, parking is a challenge, and the highway system that intersects the city doesn't have enough lanes to handle the traffic it bears (avoid the Schuylkill Expressway westbound especially).
Bottom line: Use all the other transportation options you will have access to while visiting. The PHLASH bus runs throughout the downtown area daily from May through Labor Day and then on weekends after Labor Day through December; it costs $2 per ride or $5 for an all-day pass. The public transit system, known as SEPTA, is pretty easy to navigate: The one-day Independence Pass ($12 per individual or $29 for a family of up to five people) is a great bargain for getting around the city and beyond. We plan our visits to be either all-walking or all-transit days, and use the pass for the latter.
The heart of Philly is the Old City district, which is dominated by Independence National Historical Park . This four long-city-block area is anchored by Independence Hall (and the Liberty Bell Center at the south end and the Independence Visitor Center and National Constitution Center at the north end). On the periphery of these are an almost overwhelming number of other sites you can visit. Anything in the national park is free to visit (but you do need to get a timed ticket to visit Independence Hall; visit nps.gov/inde for instructions). Most other sites outside the park charge nominal admission fees or offer guided tours for a modest cost.
Some of our "Other" favorites include: Christ Church where you can sit in George Washington's pew (2nd Street above Market Street - NOT on North American Street like Google Maps will tell you; and its Burial Ground where you can toss good-luck pennies on the graves of names you recognize (5th and Arch streets); the Benjamin Franklin Museum (316-318 Market St.); the Betsy Ross House (239 Arch St.); and Franklin Square (not exactly historical but the carousel and putt-putt golf might be a welcome break; 200 N. 6th St.).
Another must-do within this area is a meal at City Tavern (138 S. 2nd St.). It's a rebuilt version of the 1772 original, which was a favorite of John Adams and other members of the Continental Congress. The wait staff dresses in colonial garb, the water comes in heavy metal goblets, the menu tends toward lightened-up colonial fare and historically significant foods like Franklin's tofu (he introduced the stuff to North America - who knew?).
And then there's the Other Philadelphia that family members of all ages will enjoy. Start your day with breakfast at the Reading Terminal Market (12th and Arch streets); It's like our North Market only much, much bigger. You can eat a cheap plate of apple-cinnamon French toast and turkey bacon at the counter of the Amish-run Dutch Eating Place, or snag a bag of Beiler's Hand Rolled Doughnuts.
The Franklin Institute (222 N. 20th St.) was one of the first science museums in the country, packed with COSI-like exhibitions (and COSI membership gets you free admission here). The two-story-tall marble statue of Franklin, though, is unique to Philly, as is the one-story-tall human heart you can walk through.
Not too far from there is the Please Touch Museum (4231 Avenue of the Republic), a children's museum geared toward the 7-and-younger crowd: Their "big" claim to fame is the "walking piano" keyboard created by a local artist and featured in the movie Big. A COSI membership also gets you in free here.
The Philadelphia Museum of Art (including the Rocky statue and steps; 2600 Benjamin Franklin Parkway); and the Rodin Museum of sculpture (2154 Benjamin Franklin Parkway); are must-sees for the art lovers in the family (and a Columbus Museum of Art membership gets you into both for free).
Then hop the 32 bus down to South Street and visit Philadelphia's Magic Gardens (1020 South St.) - two city lots whose buildings have been hollowed out and tiled over in an exhilaratingly crazy mosaic of mirror pieces, ceramics, bottles, bike wheels and other "found" items. After that, you can continue east on South Street where you'll have your pick of cheesesteak vendors: That's the artery-clogging delicacy native to Philly (Jim's Steaks, 400 South St., is probably the most authentic; Ishkabibble's, 337 South St.,the most unusual).
A visit to the Philadelphia Zoo (3400 W. Girard Ave.); is worth at least half a day: Like many other Philly institutions, it's another "America's first," dating to 1859. It's compact (42 acres; by comparison, the Columbus Zoo and Aquarium has 580), but packed with a superb primates collection, as well as really unusual nocturnal and rare/endangered species exhibits. A Columbus Zoo membership gets you a 50 percent discount on admission here.