Activity: Aqueduct Park. Metro Stop: Subagusta. Cost: Free. Hours: Sunrise to sunset.
This beautiful open space will be a breath of fresh air after being in the congested city for 5 days. It's home to a few aqueducts built in 52 BC! These aqueducts were what set Rome apart way back when. Fresh water is a big deal; just think how inconvenient it is when your water gets shut off for a while! It's a bit off the regular tourist path, but your kids will love to run around and you will love the photo ops.
It's an hour away, so bring a lunch and expect to hang out there for most of the morning and afternoon. There's a nice little park on the way back to the Subagusta Metro Station.