As the crowded subway train approached Harvard Square station, coming from Boston, I felt the sharp turn and heard the squealing and screeching sound of the wheels against the track of the train slowing down. Look out of the window now, my friend said, and you will see remnants of the original 1912 station. Since we were still underground, the old station was shrouded in darkness, but still somewhat visible. This was part of the bus and subway station that was built in Harvard Square when the Red Line, part of the Boston area's rapid transit system, opened in 1912. The entrance to the station featured a sign announcing that the train could take you to Park Street, located next to the iconic Boston Common, in eight minutes.

When the Red Line was extended between 1978 and 1985, adding three more stops in Cambridge and in neighboring Somerville, the Harvard Square station was completely rebuilt and slightly moved from its original site. The subway tunnel was designed to follow Massachusetts Avenue, which makes a sharp, almost right-angle turn as it approaches the station. Regulars soon got used to the nails-on-chalkboard sound that welcomes them to Harvard Square. My friend and I exited the train and wandered into the enormous lobby, pausing to look at the closed ticket windows rendered obsolete by the tickets known as CharlieCards, and walked up a ramp into the bus tunnel. Despite the bright glazed red and white tiles, the tunnel looks slightly worn and disheveled, perhaps because it is one of the few areas of the original station that are still under use.

The subway and the multilevel bus and train station are part of what makes Cambridge a multilayered city: a place where daily life, traffic and transportation, parking and infrastructure happen not just at the street level, but on many layers located above and below ground. Segregating rapid transit from above-level traffic allows cars and buses to move more smoothly and to minimize jams, since it involves reducing the number of vehicles competing for space on the roads. A mass public transportation system that runs underground is also essential considering Boston's notorious winters and frequent nor'easter snowstorms and blizzards that can severely disrupt traffic, as was seen dramatically in the Blizzard of 1978, which dumped twenty-seven inches of snow in Boston.

Cambridge is also a multilayered city in the historical sense, as it is possible to see the footprint and remains of different historic periods in the buildings, in the businesses, and even in the street layout. Not only does the 1980's subway station still contain some elements of the 1912 station, the 1928 entrance to the old station has been repurposed as the iconic Out of Town News, which sells newspapers and magazines from all over the world. Furthermore, the main entrance to the station is located in a part of Harvard Square known as the Read Block, which is one of the oldest blocks in the Square and recognizable in old images.

Where in your city is it possible to see the many historic and physical layers? Are these layers visible, accessible, or more subtle? How do these layers contribute to the way your city works, to its identity, to its sense of place?

Credits: Images by Rosabella Alvarez-Calderon and linked to sources. Data linked to sources.