If there was a contest for most popular apartments in New York City, this one would be in the running as the winner. Apartment #3L at the Park Slope co-op 749 Union Street has been profiled in Lonny and Architectural Digest. It has its own Instagram account. And it was designed by Dan Mazzarini, the former director of store design at Ralph Lauren who went on to open his own design firm, BHDM. Envisioned as a black-and-white bachelor pad with a sleek, modern kitchen, the apartment is now looking for its next owner at an ask of $995,000.