Architect John A. Pearson conceived the idea of a Memorial Chamber in the Peace Tower as a national shrine: a noble tribute to Canadians who had given their lives during the Great War in France and Flanders.
In 1921, at a very early stage in the project's development, the architect decided to ask the British, French and Belgian governments to provide stone for use within the Memorial Chamber.
The Chamber's altar, Great Britain provided a block of Hoptonwood limestone. Belgium presented black marble for the wall plinths and altar steps, as well as Ste Anne marble for the clustered columns which support, at each corner of the room, the intricate fan vault. For the walls and vault, the French government gave Chateau-Gaillard stone.
The Memorial Chamber is a solemn room which encourages reflection, a sense of peace and respect. It is remarkable for its detailed Gothic Revival style, which gives the small space a lofty appearance due to the exceptional height of its walls. Placed behind an open tracery screen, the outer walls consist of a blind arcade at the lower level, surmounted by magnificent stained glass windows.

Here is a seven minute youtube video on the Memorial Chamber: