When you're talking about the T in Cambridge or Somerville, you're most likely referring to the Red Line. Connecting the major squares in both cities, it begins at Alewife in North Cambridge. 

Alewife Station is named for the nearby brook, an offshoot of the Mystic River. The brook itself gets its moniker from a species of herring that inhabits its waters. Located at the intersections of Alewife Brook Parkway and Route 2 in North Cambridge - and just a stone's throw from East Arlington - this terminus of the Red Line is the access point to the T for those living in the Northwest suburbs.

There is a garage with 2,733 parking spaces available for $7.00 for the first 14 hours, $15.00 thereafter and $15.00 for each additional day.
For cyclists arriving via the Minuteman Bikeway, Alewife Linear Park or the Fitchburg Cutoff Path, there are three secured bicycle cages with 150 spaces each.

The Alewife T area, which until the late 1960s was home to little more than a mostly vacant industrial park, a chemical factory and protected wetlands, has recently been the focus of large-scale development. Luxury residential buildings Fuse Cambridge, Atmark, the Wyeth and Hanover Alewife are all within walking distance of the station, and in February, 2017 construction began on the Alewife Research Center, a 223,000-square-foot  research and development/lab building that will have a first-floor retail space. It is scheduled to be completed in the summer of 2018.

Currently, the area has multiple industrial/corporate buildings in addition to the residential ones, so despite the fact that this station is not located in a bustling square, there are a few local businesses and services to note.

Directly across from the station is the original location of the now multi-city Summer Shack, a family-friendly classic New England seafood restaurant helmed by renowned chef, cookbook author and restaurateur Jasper White. With a menu that runs the gamut from raw bar to "chowdah," and fried clams to "lobstah" the Shack greets many a weary T-traveler with homey hospitality.
If seafood isn't your thing, fear not - the street level of Alewife houses a Bertucci's, complete with outdoor patio in the warmer months.
Need to grab a bite to go? Alewife has you covered there, too. Inside the station you will find kiosks offering a plethora of snacks for purchase as well as an outpost of the local standby, Dunkin' Donuts.

Alewife serves as the gateway to the work day for many parents, and there are two childcare options conveniently located nearby: Sunrise Learning Academy, for early education and childcare, and Panda Bilingual Daycare, a Mandarin-English Montessori school.

In true Cantabrigian style, the Alewife T Station is not purely functional. It is also home to six works of public art, as part of the pioneering Arts on the Line program which brought art into T stations in the late '70s and early '80s - the first of its kind in the country and a model for similar installments throughout the U.S.

MBTA bus lines (the 62, 76, 67, 79, 84, 350 and 351) serve the station's enclosed bus depot.

From Alewife, the Red Line stops underground in Davis Square in Somerville, then Porter, Harvard, Central, and Kendall Squares in Cambridge before surfacing to cross the Charles River into Boston.