As Canada's Centennial approached, many events were planned in celebration. The country re-discovered its origins, especially the meetings of 1864 in Charlottetown and Quebec. In 1974, the federal government and the government of Prince Edward Island entered into an agreement whereby Parks Canada undertook to restore the building and refurbish certain interior areas to 1864.
Determining the original nature of the building was not always easy. Numerous and varied alterations confused or obliterated much of the original structure and appearance. Historical and archaeological research was helpful, while investigations of the building confirmed some changes and revealed others. For example, the original floor boards gave evidence of curved railings at both ends of the Confederation Chamber and of a semi-circular dias against the west wall. These features had not appeared in early photographs, although the dias was mentioned in original construction records.
Beginning with the exterior, the sandstone was patched and cleaned and some stones replaced. A roof of slate and copper was installed according to original specifications. Chimneys and skylights were reconstructed.
The interior had seen much painting and plastering. Careful research resulted in the accurate reproduction of original paint types and styles. Some restoration, as in the Confederation Chamber, was formal and refined, even ornate. Other areas received more simple treatment in keeping with the original.