The hook here is a good one: The entrance and public areas (as well as 18 guest rooms) are in the former Charles Street Jail, built in 1851. The granite edifice has enormous windows that illuminate an octagonal atrium. An adjoining 16-story tower is home to the rest of the guest rooms and the fitness center, which was completely renovated in 2014. Accommodations and bathrooms are large and luxurious, all cool neutrals with stainless-steel accents. Units on the river side of the building also face busy Storrow Drive, but the view in the other direction is of a hospital; given a choice, I’d opt for the river and ask to be on the highest possible floor.