Nauset Construction and developer 3MJ Realty have completed the conversion of the former Conrad’s department store in Boston’s Downtown Crossing into a 27-unit luxury apartment complex.

The Winter Street property next to the Orpheum Theater contains a mix of two-, three- and four-bedroom units. 3MJ Realty redeveloped the 32,000-square-foot property most recently used as office space.

Based upon plans by Schopf Design Assoc., the original stone facade of the 19th-century Beaux Arts building has been restored with the historic architecture integrated into the modern exterior and interior design. Three light wells extending from the third floor to the roof were created to supplement the natural light provided by large windows of the original department store, which were restored.

The Conrad’s apartments feature 11-foot loft-style ceilings, original exposed brick walls and a mix of resilient wide-plank and ceramic tile flooring.

The redevelopment plan addresses the shortage of three- and four-bedroom apartments in the downtown and Seaport, 3MJ Realty Principal Morris Naggar said in a statement. Two-bedroom units ranging from 730 to 750 square feet are being marketed for $3,500 to $3,800 per month, while four-bedroom units range from 1,180 to 1,325 square feet and rent for $6,000 to $7,200.

3MJ Realty manages a 250,000-square-foot portfolio in Boston and Cambridge.