I have three buildings today, of two uses. The first is one I've passed by on countless occasions. It's one of the hydro substations in the city, located on the west edge of the Glebe. The building's still in use, older than the more recent (and utilitarian looking) substations one comes across on a regular basis. Something about the building appeals to me.
Elsewhere in the Glebe, this is First Avenue Public School. The oldest part of the school dates back to 1898.
And down in Old Ottawa South, this is Hopewell Avenue Public School. Its oldest portion dates back to 1910, and the school had a major expansion decades later. The last shot, taken on another day, shows the expansion as well.