Complex sentence: The film premiered on Saturday, March 6th, 1965 at the City Hall Cinema, 170 Nassau Street, in Manhattan, the site of Mekas's "Film-Makers' Cinematheque" at the time.
Split into simpler sentences: The film premiered on Saturday, March 6th, 1965 at the City Hall Cinema, 170 Nassau Street, in Manhattan. The site was the home of Mekas's "Film-Makers' Cinematheque" at the time.