In Ottawa, the tradition Trooping of the Queen's Colour ceremony takes place on Parliament Hill or at Rideau Hall on occasion. The reviewing officer in the ceremony is the Queen, with members of the Royal Family, the Governor General, the Minister of National Defence and the Chief of the Defence Staff taking her place in her absence. The participating units in the parade include personnel of the Governor General's Foot Guards and The Canadian Grenadier Guards, both of which are part of the "ad hoc" Ceremonial Guard.