At Lowell, the Park itself is free, meaning you can go through the mills and museum at your own pace. But you can also take a guided tour, which isn’t free and we found very good. There’s more info, plus you’re guaranteed that they’ll fire up whatever equipment they can. Typically that will include a handful of the looms out of dozens, which are loud enough for them to hand out ear plugs. I can’t imagine what having the entire floor of looms running would be or how anyone working there didn’t go deaf. There’s at least one other building on the tour where they fire up one of the water-powered wheels. Plus the tour goes on the trolley instead of having to walk.

It’s about a mile from the commuter rail station. I’ve never walked it, but imagine it’s walkable, and certainly cab/Uber/Lyft should be doable. There are also some nice restaurants in Lowell.

I forgot to mention: pay attention to the commuter rail schedules. All of these trips are opposite the usual commuter traffic, so they’re not going to be frequent and the last one of the day can be early.