 The first broadcasts came from DuMont 's 515 Madison Avenue headquarters , and it soon found additional space , including a fully functioning theater , in the New York branch of <unk> 's department store at <unk> Street and Broadway . Later , a lease on the Adelphi Theatre on 54th Street and the Ambassador Theatre on West 49th Street gave the network a site for variety shows , and in 1954 , the lavish DuMont <unk> @-@ Centre opened in the former Jacob Ruppert 's Central Opera House at 205 East 67th Street . 
