The Bushwick was built by showman Percy Williams with William McElfatrick as architect, and first opened on September 11, 1911, as a vaudeville house. A year later, Williams sold it to Keith's, which explains how it eventually became part of the RKO circuit. By today's standards, the auditorium was very old-fashioned, with boxes overlooking the stage and a painted mural on the ceiling over the stage. In 1926 and again in 1929, it had some alterations done by Thomas W. Lamb. In 1938, more "streamlining" was done by Max Weinberger. The Bushwick closed around 1969 and then served as a church before being abandoned.
I stumbled upon this theatre in the mid 1990s when it's fabulous terra cotta cherubim peered in at me while I was riding the Z train through Brooklyn. You can see photos of the decayed building at FadingPad and Forgotten-NY.
I returned in 2003 to find the building under renovation. The interior apparently had decayed beyond recovery, although it would probably have been in the owner's interest to say that even if it wasn't true to keep all us single-minded preservationists at bay. However, this struggling neighborhood has no use for an old movie palace, so the shell was restored quite nicely for the new ACORN High School for Social Justice.