Very popular place with the locals. There are live bands every night, sometimes even directly from Ireland. Lots of stone structures, making the pub feel authentic. Unfortunately, I missed the Irish Dancing lessons that happen Monday nights at 8, but I hear they're a hoot. They don't have a huge selection of beers, but they have enough to please a variety of people, plus they have a few wines, hard ciders, and non-alcoholic beers. Food from their lunch menu is served up until 5pm when they switch over to their dinner menu. Try their Guinness Beef Stew for dinne -- excellent!!
Dress Code: Casual is fine.
Go to the Burren in Davis Square in Somerville. It is truly like stepping into a pub in England (and Ireland too, I hear) Up front they have traditional Irish music, and the bar serves more different types of beer than you can imagine. Out back they have different bands playing. Try to go see "Jim Ambrose and the Swamptones" they are a truly awesome blues band. They mix lots of the blues type music that you are familiar with, and they have lots of REALLY GREAT originals too!
Dress Code: Wear anything. - My sister from California has noticed that most people seem to wear something emblazoned with the brand name "North Face" ha ha ha - Oh and keep in mind.. Boston and most of it's neighborhoods are all non-smoking...
The Burren is a nice place to hang out, located in Somerville (Davis Sq). I usually go there every sunday night. A very talented singer, Danielle Miraglia, hosts the singer/songwriter series, starting at 8pm and plays her own tunes from 10pm to 12am.
Check it out, you will definately have a great time...
See also, The Kendall Café in Kendall sq., Johnny D's in Davis sq., Lizard Lounge between Harvard and Porter.
Dress Code: Casual