The CTA station at State and Lake is closing so it can be demolished and rebuilt.
Some commuters learned about the closure as they were heading in to work Monday.
Crews brought in heavy machinery and got right to work, as they begin the massive overhaul of the State/Lake train station.
Overnight, crews shut down entrances of the station and posted new signage as major renovations are now underway. This is part of a three-year long project.
"It's a little frustrating," commuter Megan said. "I live on the north side. I am a graduate student at UIC and I need to get over to the medical district for school everyday.
SEE MORE | Our Chicago: Replacing the historic State and Lake CTA station
The 130-year old station has the fifth highest ridership across the CTA.
Brown, Green, Orange, Pink, and Purple Line trains are bypassing the station until construction wraps up.
The project includes adding elevators so the station is wheelchair accessible.
Platforms will also be widened to improve safety and add comfort to riders.
The Chicago Department of Transportation says there were other important factors that were considered in this project.
"Safety and visibility, making sure that there are no maintenance concerns," Anne Zhang, deputy commissioner for the Chicago Department of Transportation Division of Engineering, said. "It is an old station like you mentioned, and we want to make sure it's top notch and reflective of a world class facility for a world class city like Chicago."
Commuters in the Loop had to look for alternate routes to get to their destination as this project is expected to wrap up by 2029.
"I use it quite often," commuter Raymond Riley said. "I think it's disappointing. It's going to cause a lot of trouble I think for passengers to find other ways to go."
"We'll see how it works, take the first couple of weeks, we'll see what station works for us," commuter Tom said.
Riders are being asked to use nearby train stations in the Loop, such as Clark/Lake and Washington/Wabash.
CTA staff have been on hand morning redirecting commuters to the closest stations.