Check out this great post from David McClelland's blog, The Ottawa Project. It's about the evolution of downtown Ottawa around the Union Station.
Using a series of overhead images, David traces the evolution of the area that now includes the Rideau Centre, the National Arts Centre, City Hall, and the Government Conference Centre.
David writes: "I think, looking at this sequence of images, what’s truly amazing is the fact that this covers maybe a little more than one square kilometre of Ottawa. The changes here are incredibly drastic over a relatively short period of time in the grand scheme of things, and changes like this occured all over the city for periods even longer than this. We tend to think of the places we live as being very permanent, but in reality, they’re extremely fluid. You only need to step back a little bit, and you can see that fluidity in action."
Related: Ottawa History Guide