Excalibur Climbing Wall, Groningen, The Netherlands

Gym climbing is becoming an increasingly popular urban sport and provides many people with the opportunity to try some aspects of the sport of rock climbing. Bouldering gyms focus on bouldering rather than roped climbing.
Wall types
The simplest type of wall is of plywood construction, known colloquially in the climbing community as a 'woody', with a combination of either bolt-on holds or screw on holds. Bolt-on holds are fixed to a wall with iron bolts which are inserted through the hold, which will have specific bolt points, and then fixed into pre-allocated screw-threaded holes in the wall. Screw-on holds are, by contrast, usually much smaller, owing to the nature of their fixing. These holds are connected to the wall by screws which may be fastened anywhere on the wall's surface.