The Memorial Window was commissioned to celebrate the Sesquicentennial of the Cathedral (1832 - 1982) and was designed and made by Christopher Wallis, from London Ontario who also designed a number of new stained glass windows in Rideau Hall. It was dedicated by the Right Reverend Edward K. Lackey, Bishop of Ottawa.

The window is a dramatic stylistic shift from the Decorated Victorian style seen in the rest of the Cathedral, using transparent glass and a more mosaic-like technique. The central figure of the Lamb of God is superimposed on a series of blue wavy lines representing the joining of rivers: west-to-east flow is that of the Ottawa River; the north, the Gatineau River; the south, the Rideau River and Canal system. The Cross is flanked by symbols of faith and images of the Cathedral, the city, the nation's history (e.g. the Anik II Satellite in the lower right panel), the natural world and the diverse faces of contemporary society.