Union Station might be one of Toronto's most beautiful buildings, but it's also one of our most interesting. As the central railway hub in the city, it has a fascinating history filled with oddball details, hidden stories, and a number of secrets.

Here are some thing you didn't know about Union Station.

1. What we call Union Station is actually the third such rail hub in Toronto, with the first one dating back to 1858. It was little more than a shed, but the second version was a majestic structure that opened in 1873 and was renovated and expanded in 1896.

2. Primary construction on the current building was completed in 1920, but the station didn't officially open until a 1927 visit from the Prince of Wales because the network of approach tracks had yet to be completed. It would take until 1930 for the train shed to be finished.

3. The tunnel connection between Union Station and the Royal York Hotel was one of the first portions of the underground network that would become known as the PATH.

4. The 22 columns that decorate the Front Street entrance to the building are made out of Bedford limestone and each weigh 75 tons.

5. There's an abandoned tunnel connecting the Union Station rail terminal and the TTC station of the same name. It was built in 1953 and used until about 1977 when Royal Bank Plaza opened. By this point, it's been mostly filled in.

6. Union Station was nearly demolished in the 1970s. The joint vision of CN and CPR, Metro Centre would have been the biggest downtown redevelopment project in North American history, but Union Station wasn't part of the plans. It was to be replaced by a modern transit hub.

7. The station used to be absolutely filthy. Decades of coal use had left many historical structures covered in soot, but Union's Indiana and Queenston limestone exterior took a real beating until clean up efforts in the 1980s.

8. The Scotiabank Arena (former ACC) was almost built on top of Union Station. Before the Toronto Maple Leafs bought the Raptors and moved both teams to the facility, the company had a grand plan to build an arena/stadium to house both teams that would be located around where the train shed is now.