It's easy to take the CN Tower for granted when living in Toronto. Thanks to its soaring height, it's become a fixture in our peripheral vision, peeking into the frame of so many views of the city.

It's also the most relied upon directional marker, serving as the best way to orient yourself when temporarily lost. But while the upper features of the tower, most notably its two pods, have become ingrained in our consciousness, it was quite a different story during construction.

For a few years in the 1970s, the tower was a downright awkward addition to the skyline, soaring like a concrete monolith above the mostly undeveloped skyline of a city just starting to go through a huge growth spurt.

Construction on the CN Tower began on February 6, 1973 — 45 years before the writing of this post. And while an ingenious construction method using poured concrete meant that the lower half of the tower shot up rather quickly, it wasn't until June 26, 1976 that it officially opened.

Between these two historic dates, people who lived in Toronto were treated to one of the most remarkable construction projects ever undertaken. The world's tallest structure (at the time) steadily rose above the city, and nothing's been the same since.

Behold, what the CN Tower looked like as it was built.