Downtown is a very fun, walkable area full of restaurants, breweries, distilleries, shops, bars, and parks, with 4 easy-to-access parking garage options.
Hiking and scenic overlooks just outside of Frederick. Free park access for all lots on the mountain (recommend starting from the Tea House or Lower lot)
Waterfalls. Need I say more? Has both accessible trails and hiking trails to the falls
Can be a shorter adventure or a full day trip
Fun nature center with local fauna, walking trails, and picnic areas. Stop by Downtown Middletown for ice cream on your way back