Constructed in 1856, it was recognized by both the Government of Canada[1] and the City of Toronto[2] as being of historic significance, but portions of it collapsed and it had to be demolished in 2007 due to neglect.

At three and half storeys, the building featured buff brick with decorative brickwork and stone detailing, a symmetrical façade, a gabled roof and dormer windows.

[2] In 1949, the interior was converted to a rooming house, and a number of changes were made to the exterior, including the conversion of the southeast corner to a storefront.

That evening, a city building inspector recommended that Walnut Hall be demolished for safety reasons, and the demolition was undertaken that night.

[3] In 2008, Heritage Canada included Walnut Hall in its annual list of "Worst Losses", referring to the building's neglect and demolition as "a case of architectural euthanasia".