Canada's federal properties are not protected.

The Dominion Observatory buildings are not part of the Civic Hospital/Experimental Farm land deal. But lease agreements are amended all the time.

The Sir John Carling Building, 930 Carling Avenue in Ottawa.

In 1971 Arthur Covington wrote a letter to Prime Minister Pierre Trudeau asking the PM to save the Dominion Observatory.
 The following terms mean nothing:
1.)  National Interest Land Mass -The Farm is a National Interest Land Mass, so is the Greenbelt.
2.)  National Historic Site of Canada.
3.)  Classified Federal Heritage Building and Recognized Heritage Building.
Fort York in Toronto is a National Historic Site of Canada but much of land has been divested and sold to condominium developers.Montgomery's Tavern on 2384 Yonge Street was a federal post office.The Kingston Penitentiary may lose 11 limestone buildings, the guard towers and perimeter walls.

The land that was allocated to the Civic was zoned as L3 until the year 2017:
Permitted Uses
agricultural use
environmental preserve and educational area.
museum-limited to agricultural museum-(Agriculture Canada officials wanted to preserve the SJC  cafeteria annex and convert it to a visitor's centre and a museum for an insect collection. But the Ottawa Civic is planning to demolish it.)
on-farm diversified use
park limited to agricultural use (The Sir John Carling Building was located on Agriculture Canada land, but the AAFC land was surrounded by Queen Juliana Park; and the park was a gift to the citizens of Canada in 1976.)
research and development centre
urban agriculture
A Zoning By-Law Amendment and Official Plan Amendments have been submitted for the new Ottawa Civic Campus site at 930 Carling Ave. and 520 Preston Ave.
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The Royal Observatory in Greenwich, England was designed by Sir Christopher Wren and is protected by the United Nations agency UNESCO. Ottawa's Dominion Observatory is modeled after the Royal Observatory.An official from Canada's federal government signed the UNESCO treaty.
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Part of Queen Juliana Park and the Dow's Lake parking lot encompass 5.2 ha. or 12.8 acres. They are designated as Mixed-Use Centre. To see the map Google "Ottawa Hospital Official Plan and Zoning By-Law Amendments" May 9, 2017.

This part of Queen Juliana Park is zoned as  Mixed-Use Centre.. The Sir John Carling Building on Agriculture Canada land can be seen in the distance.

Mixed-Use Centre- Sections 191 and 192
The purpose of the MC Zone is to...accommodate a combination of transit-supportive uses such as:
-offices, secondary and post secondary schools, hotels,hospitals, large institutional buildings;
-community recreation and leisure centres,
-day cares centres, retail uses, entertainment uses,
-services such as restaurants and personal services businesses, and
-high and medium-density residential uses.