Epstein served as the executive architect for the D48 office building, a Class-A building located in Warsaw. D48 is a ¬45 million, 26,000 square meter (280,000 square feet) development that also includes ground floor retail and a restaurant.

D48 is located at the intersection of Domaniewska and Postepu and features convenient access to public transportation, including trams and bus lines, nearby high-speed railway station, as well as the Warsaw subway. D48 has two distinct facades; an 11-story structure on Domaniewska Street and an 8-story building on Postepu Street. The D48 development also features spacious terraces located on the 7th, 9th and 10th floors which will provide grand views of Warsaw's City Centre as well as a unique spot for tenants to relax or host informal business gatherings.

D48 also has fully glazed façade, which provide extensive daylighting opportunities for its tenants. The development also provides two underground parking levels totaling 435 parking spaces and there are also 45 surface spots as well as ample charging points for electric cars.

The main entrance to D48 has a spacious reception lobby accessible off of Postepu Street and also includes outdoor green areas with a landscaped courtyard and furniture as well as bike-friendly facilities such as bicycle racks, changing rooms and showers.

D48 is Penta's first development project in Poland.