Liberty Hotel, Boston
As the Charles Street Jail from 1851 to 1990, the building grew infamous for its squalor. Now it's gaining fame for its sense of humor and beautiful preservation of historic jail catwalks and cells.
The Liberty Hotel opened in September 2007 with 18 luxury rooms in the historic structure, 280 rooms in a new tower, the Alibi Bar (in the former drunk tank) and two restaurants: Clink and Lydia Shire's Scampo ("escape" in Italian).
For romance: The Liberty's Guilty Pleasures Romance Package with chocolate-dipped strawberries, an intimacy kit, etc., is popular year-round. Packages start at $415.
Malmaison Oxford Hotel, Oxford, England
Malmaison Oxford, about 60 miles from central London, encourages guests to bring their own handcuffs. This former prison blends comfy beds, power showers and mood lighting with wrought-iron-work stairs and 3-inch-thick steel doors. There are 40 cell rooms (each created from three cells: two for the room, one for the bath) and 54 rooms that were never cells.
For romance: Love Suite Love package starts about $311 a night and includes a suite, Champagne, chocolate-dipped strawberries, aromatic oils and candles and breakfast.
Four Seasons Hotel Istanbul
This 65-room hotel, built in 1918, was reborn as a Four Seasons in 1996. The Turkish prison's original wooden doors and its courtyard watchtowers (now housing elevators) were preserved along with other architectural features.
For romance: Choose a bed-and-breakfast package, which starts about $471 a night.
Hotel Katajanokka, Helsinki, Finland
The confining bars are gone from the Hotel Katajanokka, which opened as a Best Western in May 2007, but the outer red brick walls and central hallway of the former Helsinki County Jail remain. Each of the 106 rooms (including three junior suites) was created from two or three prison cells.
From 1837 to 2002, the jail housed inmates awaiting trial. For romance: Skip Valentine's Day and go in November or December when you can cuddle through the long, dark night, or go in July or August for a day that won't end. Katajanokka's best romance package includes a glass of sparkling wine and breakfast for $192 a night for a premier double room.