Back before cars took over, horse-drawn buggies used to rule Chicago’s roads. When people needed to cross the river, a tunnel was dug below the river along LaSalle Street that ran between Randolph and Hubbard streets. It was built between 1869 and 1871, was 1890 feet long and cost $566,000, which is about $10 million today.
The tunnel had three lanes: two for carriages and one for pedestrian foot traffic. In started to fall into disrepair in the 1880s and 1890s, but was eventually rebuilt to allow for electric streetcars to travel through it and remained in operation until 1939. Today, you can see the northern entrance, but it merely goes down to an alleyway that runs below the street. (Thanks to Calumet412.com for the photo.