The structure includes 22 stone columns which are 40 feet tall and weigh 75 tons. The highest point, in the centre of the terminal, is 112 feet high. The Great Hall is the centre of the station with staircases at either end leading to the Arrivals Concourse. The room is 250 feet long and 84 feet wide. On either side are arched windows 4 storeys high. To show the impact Union Station, and the railroad has made on Canada the Great Hall has names of cities and towns carved around the room. These names are the places where growth and development were stimulated by passenger trains.

In recent years the station has become a terminal for both rail services and a link in the Toronto subway system. It has also been designated a railway heritage structure under the Railway Station Protection Act passed in 1994. According to the TTR, Union Station is the only large railway station on the continent which provides for through-train operation. This design is an important aid to efficient railway operations. TTR facilities in and around Union Station include 25 1/2 miles of circuited track and 4 miles of station platforms.

Union Station the largest and busiest rail station in Canada with more than 24 million passengers in 1996. It functions as a for passenger rail, commuter trains, subway and bus service. The station is also VIA Rail's busiest terminal with over 50 percent of all VIA arriving and departing passengers using the station. In addition, over 120,000 commuters use the GTA's GO Train service every day to get to work in the around Toronto.