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Building 20

Québec, Quebec, Canada

Formally Recognized: 1993/06/29

General view of Building 20, showing the rooflines, reflecting the complexity of the building and the simple lines of the building, which offset the complexity of the design, 1980.; Department of National Defence / Ministère de la Défense nationale, 1980.
General view
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Other Name(s)

Building 20
Ball House
Maison Ball
Former Observatory and Ball Tower
Ancien observatoire et ancienne tour de la boule
The citadel, Building 20
La Citadelle, bâtiment 20

Links and documents

Construction Date(s)


Listed on the Canadian Register: 2005/08/03

Statement of Significance

Description of Historic Place

Clearly seen from the harbour and aligned on the meridian for observation purposes, Building 20 in the Québec Citadel National Historic Site of Canada, also known as the Ball House, and Former Observatory and Ball Tower, is a compact, tall, two-storey stone structure of several architectural shapes. The rectangular section with a gabled roof was the former observatory and the square section formerly housed the ball installation topped with an antenna. The building is entered from the ground floor of its small porch, which joins the two buildings and whose roof supports an old wooden. The designation is confined to the footprint of the building.

Heritage Value

Building 20 is a Classified Federal Heritage Building because of its historical associations, and its architectural and environmental value.

Historical Value
Building 20 is one of the best illustrations associated with the development of astronomy in Canada, in the field of time measurement in particular. Building 20, is the oldest building in Canada designed for use as an observatory. It also housed one of the first devices used in a Canadian harbour to measure time and to signal the time using a ball, a service that proved vital to ships. Building 20 is also associated with Edward David Ashe, who served as the first director of the Québec Observatory from 1850 to 1883 and is credited for laying the groundwork for the next half-century of practical astronomy in Canada. Because of his solar research, he is considered to be Canada’s first astrophysicist.

Architectural Value
Building 20 is an excellent example of functional design with a very good harmonious and attractive arrangement of architectural forms. Its unique shape is attributable to its dual function of housing an astronomical observatory and supporting a facility that could be used to communicate the exact time to mariners using a ball.

Environmental Value
With part of the building extending higher than the walls of the bastion where it is located, Building 20 can be clearly seen from the harbour and was purposefully aligned with the meridian line. Although not a military structure, it visually harmonizes with the other buildings in the Citadel and its materials, height and design reinforce the historical character of its National Historic Site of Canada setting in Mann's Bastion located in the Québec Citadel. The building is hidden from view from the centre of the Citadel and is surrounded by manicured lawns, fortification walls, the sallyport to the exterior of the Citadel and the rear of the former hospital.

Sources: Former Observatory and Ball House, Building No. 20 Québec, Québec, Federal Heritage Building Report 88-161; Former Observatory and Ball House, Building 20, The Citadel, Québec, Québec, Heritage Character Statement, 88-161.

Character-Defining Elements

The character defining elements of Building 20 should be respected.

Its functional design, and arrangement of architectural shapes, construction materials and techniques as manifested in;
-its compact, two-storey masonry building, roughly L-shaped in plan and composed of a rectangular gabled-roof section and square section topped by an antenna, joined by a connecting porch whose primary function was to absorb the vibrations produced when moving the ball;
-the rooflines, reflecting the complexity of the building and the simple lines of the building, which offset the complexity of the design;
-the wooden turret pierced by twelve small windows and located on the roof of the porch and the mechanism that allowed the roof to turn;
-its regularly-coursed stone masonry;
-its simple decorative element of the band course marking the line between the ground and first floors of the observatory;
-the style and manufacture of the windows, doors and roofs;
-elements of the interior related to the building’s primary use.

The manner in which Building 20 reinforces the historical character of its national historic site of Canada setting located in Mann’s Bastion at the Québec Citadel.




Recognition Authority

Government of Canada

Recognition Statute

Treasury Board Heritage Buildings Policy

Recognition Type

Classified Federal Heritage Building

Recognition Date


Historical Information

Significant Date(s)


Theme - Category and Type

Function - Category and Type



Military Defence Installation

Architect / Designer



Royal Engineers

Additional Information

Location of Supporting Documentation

National Historic Sites Directorate, Documentation Centre, 5th Floor, Room 89, 25 Eddy Street, Gatineau, Quebec

Cross-Reference to Collection

Fed/Prov/Terr Identifier




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