Baltimore is an ideal spot for a short trip from Philadelphia. It’s nearby — you can get from Baltimore Pike to Baltimore’s Inner Harbor in 90 minutes — and once there, the family-friendly options are close enough that you can walk to most, drive to some and take a water taxi to others. (There isn’t a water Uber yet, is there?)
Head south
If you are the kind of parent who wants your kids to learn something even while they are on the road, explain the significance of the Mason-Dixon Line when you cross into Maryland. You won’t be able to avoid it, since it runs along the Pennsylvania and Delaware borders. It’s early in the trip; they won’t roll their eyes too much.
Once you get to Baltimore, you might as well make the Inner Harbor your base camp, since much of the city’s tourist venues encircle the water there. If you haven’t been to the National Aquarium before, do go. It’s spectacular fun. But if your kids have been there for a class trip or on a previous visit, skip it and explore less-famous sites, like the Maryland Science Center. It’s only a 10-minute walk from the Historic Ships that dot the harbor. With a planetarium and an IMAX theater, the Center is comparable to the Franklin Institute back home.
Just around the corner is the American Visionary Art Museum, dedicated to self-taught artists, like the Pennsylvania junk collector whose Family of Robots, made of household electronics and car headlights, will delight the kids.
Get weird
Now that you’ve done something smart and educational for the kids, why not head in a more frivolous direction? Ripley’s 
Believe It or Not! is just off the harbor. If the kids don’t know about Ripley’s, you could try and explain its long fascination with the odd/weird/strange. Or you could just take them inside and let them discover for themselves. Aside from the expected Ripley oddities, there’s a mirror maze and a 4-D theater. Those require additional tickets, but if you can hold off until after 4pm, it’s a little cheaper.
Once back in the fresh air, look for a water taxi to take you over to Fell’s Point. You could walk, but it’s a bit of a hike, the kids are probably hungry and, did we mention, it’s a water taxi?
Fell’s Point and pirates
You can catch a water taxi right in Harborplace for the short trip across the water to Fell’s Point, one of oldest neighorhoods in Baltimore with cobblestone streets, restaurants and small shops. Sound familiar? Probably, but once you sit down for lunch, we suggest you look for crabs and crabcakes, not hoagies and cheesesteaks.
After lunch, explore Fell’s Point’s shops and stop in its Broadway Market, just renovated to house local restaurants, an ice cream shop and a big, pet-friendly outdoor patio.
All rested? Good, let’s go pirating! Just a couple blocks from Fell’s Point is Urban Pirates, where they dress the family up as pirates and take them on an hour cruise filled with swashbuckling songs, water cannons and plenty of “aaarrrrr matey.” It sets sail six times a day.
If all that buccaneering has the crew too wound up, catch a ride over to Walters Art Museum. It’s downtown, away from the harbor, but it offers a respite of more than 36,000 pieces of art from 5,000 BC to the modern day. And, hold on to your wallets, it’s free. A couple miles away is the Baltimore Museum of Art, which is also free.
We think that sounds like a pretty full day. Whether you choose to end it with a drive home or some more crabs and a night in a hotel is up to you.
It’s close; its tourist district is compact; and there’s plenty for a family to do for a day or overnight trip.
