Epstein provided Architect and Engineer of Record services in conjunction with design architect, Helmut Jahn, for the Cosmopolitan Tower, a high profile mixed-use development located on Twarda Street in the center of Warsaw, Poland. This 44-story high-rise tower includes 252 high-end apartments, office and retail space, as well as an underground parking garage.

The tower includes 252 apartments ranging from 52 to 350 square meters. Cosmopolitan Towers' ground floor along Twarda Street provides commercial space for shops and services; the underground was designed to accommodate a 300-vehicle car park.

At the time of construction, the Cosmopolitan Tower was the second tallest residential building in Warsaw and third tallest in all of Poland.