This Boerum Hill luxury one bedroom has a rooftop studio that once housed Ex Lax test monkeys

Today in fantasy apartments is 423 Atlantic Ave. #5E, listed for $1,675,000. The one-bedroom co-op is in the Ex Lax Building (yes, that Ex Lax), and has a loft-like layout.

What takes this co-op truly over the top is the separate studio located on the roof. The personal escape has a raw metal roof that is more than 13 feet at its peak, double industrial-style doors, and clerestory windows with original hardware (it was built in 1920). Beyond the fact that it's an amazing retreat/office/entertaining space, you'll also find a washer/dryer setup and utility sink in here. FYI: it sounds like an urban myth, but this rooftop structure housed Ex Lax test monkeys back in the day. Really.

The open living and dining area features eight oversized windows facing south and west, and there are 12-foot ceilings throughout. 

The professional grade kitchen has a commercial Garland stove and custom cabinets, and the dining area has enough room to seat 16 people. 

The sleeping area is partitioned off with a partial high wall that has shelves and drawers for storage. In addition, there is a walk-in closet, and three additional full-height closets. 

An expansive 600-square-foot roof deck with built-in planters provides 360 views of Brooklyn and beyond. 

Maintenance here is $2,819, and the co-op does not allow dogs, but cats are ok. The location is hard to beat, near more than 10 train lines, numerous grocery stores and independent shops, and Brooklyn Bridge Park and the Promenade.