An adjustable angle corner block for holding objects together at an angle with respect to each other. The adjustable angle corner block includes first and second plates with the proximal end edges of the plates pivotally coupled together. A holding device is provided for releasably holding the plates in a position with respect to each other such that the plates cannot pivot out of the position when held by the holding device. Each of the plates has a mounting tube coupled to the back surface of the plate such that a first mounting tube is coupled to the back surface of the first plate and a second mounting tube is coupled to the back surface of the second plate. Each of the mounting tubes is adapted for receiving a threaded end of a pipe of a pipe clamp therein.