Here's a bunch of twins in one photo:
1. Petro Canada Centre (big twin, little twin) - brown buildings at left. West tower is 53 stories, east tower is 33 stories.
2. 5th Avenue Place - two blue glass buildings perpendicular to each other at the bottom of the photo
3. Bow Valley Place - actually triplets; three white buildings near the centre of the photo.
4. Home and Dome Oil Towers - the two black buildings facing each other in the upper right portion of the photo.
5. Bankers Hall - the Silver and Gold towers near the top of the photo.