The Selwyn Library was erected in 1861, the first part of the former Bishopscourt complex to be built.

The builder was A.H. Hunter who also built the second St Mary's Church Parnell. It is a particularly fine example of Frederick Thatcher's work with its shingled roof, white painted vertical board and batten exterior, trefoil motifs under the gables and Early English fenestration.

Its roofline is very is unusual, the steep pitch of the central portion giving way to more gently sloping sections over the building's side walls. Small gables break out at right angles to the main roof ridge giving the whole roofline an even more irregular appearance. The flatter outer sections of the roof act as buttresses and inside they are supported by columns at their point of intersection with the steeper trussed section of the roof. Internal buttressing and rooflines of broken pitch are evident elsewhere in the complex but are more effectively employed in this building.

Besides its obvious architectural importance, the library for many years housed Bishop Selwyn's extensive book collection and since 1862 has been a venue for many important Synod meetings and various other meetings and functions.