In anticipation of the Mad Men season 6 premiere on AMC this Sunday night, TIME brings to you a rare insider’s tour of the Time-Life Building in the 1960s—the setting of everyone’s favorite mid-century ad agency, Sterling Cooper Draper Pryce. The Time-Life Building, designed by the Rockefeller family’s architects, Harrison & Abramowitz & Harris, opened in 1959, meaning that Don Draper et al. were some of its earliest (fictional) occupants. Time Inc. magazines like TIME, Fortune, People and Sports Illustrated still call the building home—but it must be said that, six decades later, hardly anything seen there today can match the sleek, ambitious style that defined the place, and the people who worked there, when 1271 Avenue of the Americas first opened its doors.
Editor’s note: the architects of the building has been corrected to design firm Harrison & Abramowitz & Harris