There really is no "C" line. The "C" designation is carried by all trains bound for Alewife, coming from either the "A" Ashmont or "B" Braintree branches. So the letter "C" denotes the direction of the train more than the destination.

Here is one rare case where we will actually ride one of the heavy rail lines from end to end. We will retrace the original Red Line to Harvard, and then go over a fairly new portion to Alewife. We're also retracing our steps on "familiar" rail until we get to Park Street. Commentary will continue there.

After we leave Park Street, we will come to a portal and go outside for the last time. The Charles/MGH station is the Red Line's only elevated station, and it sits partially on a bridge. The Red Line's crossing of the Charles River is accomplished in the median of the Longfellow Bridge. Vehicular traffic is on both sides.

Once over the Longfellow Bridge, we've now left Boston and will be in Cambridge for the remainder of this trip. We duck back into the subway and stop at Kendall Square/MIT, followed by Central Square.

The original subway that opened in 1912 went one more stop to a terminus at Harvard Square, near the University of the same name. That station was demolished in the early 1980's when the line was extended to Alewife. The new Alewife portion branches from what used to be the main into Harvard, and the station there was relocated northward to the new line. From here to Alewife, the stations are only about two decades old. You will notice a sharp, 90-degree turn from the original right-of-way to the newer route.

The new Harvard station features underground busways and a trackless trolley stop, A series of ramps and mezzanines carries passengers to Harvard Square at the ground level.

Almost unique about the Harvard station is that the tracks are built on two levels. Outbound trains run on top, while inbound trains are downstairs.

Beyond Harvard is Porter Square, which we will explore a bit later. Porter Square also has a bilevel platform arrangement, except now outbound trains are downstairs and inbound trains are upstairs on a balcony.

The remaining two stations in Cambridge are Davis Square/Tufts University, and Alewife. Both of these have island platforms with the tracks at the same level as one another.

Alewife is mainly a parking garage facility. The 5-story garage that sits over the western end of the station actually has express escalators that run from the underground concourse to each garage level. The exit at the east end of the station leads to a park walkway, and some apartments in the distance, but not much else. The west end of the station has a small commercial concourse, with a Burger King and a few commuter-oriented stores. A ramp leads up to street level, where there is a Bertucci's Pizza. There is a nice metal "T" sign that we might wish to use for a group photo at the street level by Bertucci's.