8 Downtown is an adult cinema and cruising multiplex on Karolou, near Omonia at the Metaxourgeio end of the centre. It is over-21s only and stays open longer than most of the city.
Inside there are screening rooms, private cabins and a darkroom. The crowd is broader than at the Gazi cruise venues: gay and bi men, some couples, and by most accounts a fair number of men who are not out.
The venue has no working web presence any more, so the phone number is the reliable way to check anything before going.