In perpetuity.

 Government properties in Canada that can never be sold or given away:

The Parliament Buildings. The Library of Parliament. Official Residence of the Prime Minister of Canada - 24 Sussex Drive. Supreme Court of Canada. Rideau Hall.The Lebreton Flats. The Greenbelt.  Gatineau Park. The Central Experimental Farm, Carling Avenue. A March 19, 1954 Cabinet Conclusion: "The Central Experimental Farm should remain an open area in perpetuity; if it were desirable to move all or part of the Farm, the land should not be used for building projects but for a park or other open area."   The Dominion Observatory Campus, Carling Avenue.   The Greenbelt Research Farm, 1740 Woodroffe.

Portsmouth Olympic Harbour greenspace- Kingston, Ontario. Prior to the 1976 Montreal Olympics the taxpayers of Ontario donated a parcel of land to the people of Kingston, Ontario. It was purchased from the Department of Fisheries and Oceans and there were conditions: The City of Kingston agreed to take over responsibility for maintenance at the end of the Olympics and said that it would be open to the public as a park. Now the property will be sold to a real estate corporation. (From:Kingston Penitentiary and Portsmouth Olympic Harbour-Opportunities and Constraints, page 18/140.)    The Royal Canadian Mint on Sussex Drive, Ottawa - Prime Minister Brian Mulroney stopped the in-progress demolition of the Classified Federal Heritage Building. Susan Delacourt article.

The Rideau Canal.  House of Commons Debates, Ottawa  June 1, 1950:

Member of Parliament George Taylor Fulford (Leeds, Ontario):"...There was a rather quaint treaty signed between Great Britain and Canada when the canal was handed over to Canada. One of the clauses said that Canada would maintain the canal system as long as the grass was green and the skies were blue."

Senate Bill S-203- An Act to Amend the National Capital Act (buildings or works of national significance.) A Senate Bill introduced by Senator Serge Joyal in 2019 will prevent the massive redevelopment, alteration and demolition of government buildings on Wellington Street across from Parliament Hill; Library and Archives Canada; and heritage buildings on the northern side of the Sparks Street Mall.  In addition, Senate Bill S-203 will block any attempt to build residential towers within several hundred meters of National Historic Sites and Monuments.

Government properties that were "under review" by PWGSC in the year 2006:

Library and Archives Canada, 395 Wellington Street, Ottawa.

Is 395 Wellington Street being "divested"?  Is that why a new LAC is being constructed on the Lebreton Flats?

Wellington Building, 180 Wellington Street, Ottawa.

John G. Diefenbaker Building, 111 Sussex Drive, Ottawa.

East Memorial Building, Veterans Affairs, 284 Wellington Street, Ottawa.

Lester B. Pearson Building, 125 Sussex Drive, Ottawa.

Sir William Logan, 580 Booth Street, Ottawa. The Energy, Mines and Resources campus is a National Interest Land Mass and cannot be sold or subdivided.

Sir Charles Tupper site, 2720 Riverside Drive, Ottawa.

National Printing Bureau site, 45 Sacre-Coeur, Gatineau, Quebec.

National Film Board Headquarters, 3155 Cote-de-Liesse Road and 120 Houde Street, Montreal, Quebec. Vacant.