The Rendezvous was located in the lower level of the Douglass Hotel.
In a May 11, 1959 conversation with celebrated jazz journalist Ralph J. Gleason, trumpeter Dizzy Gillespie shared an anecdote:
… in Philly, I had an interesting experience with Roy [Eldridge]. All the bands used to come to Philly. When I got to Philly in ’35, Roy was with Teddy Hill and Chu [Berry], and they used to jam downstairs in the Rendezvous up under the Douglas Hotel where the Showboat is now. Well, those guys used to play and I wouldn’t dare play, you know. I’d just go and listen to those guys. So one time, I remember, Rex Stewart, Duke Ellington, and Teddy Hill were there at the same time and they had a session downstairs and Roy was down there that night. And Rex, you know, Rex was Roy’s idol. Roy tells now about the time he first heard Rex play that high B flat. Roy finally found that B flat. I guess, ‘cause when he come to Philadelphia that night they was jammin’ round there and Roy started playing. Damn, Rex started crying and just tightened up and left ‘cause Roy was in rare form that night. I didn’t meet Roy until way later. I met him there, but he didn’t remember me.
Conversations in Jazz: The Ralph J. Gleason Interviews is available on Amazon.com.
All That Philly Jazz 
I lived at the corner of broad and Lombard ,in 1967 I used to walk across broad st.to a small jazz club less then two blocks from my apartment.I saw mongo stamaria ,and Arthur pryscok, among others, it was a small venue maybe 150 tops,a curved stage and a 5 dollar two drink minimum ,I can’t remember the name of the club ,but I remember the callus thick and white on his fingers he made the bongos into real jazz , I’d really like to know the name if this helps identify,it wasn’t crowed