For anyone who has ever set foot in an Irish pub, it's a familiar sight: a group of musicians clustered in a tight circle, filling the beer-stale air with the bright strains of jigs and reels. The session, as it's known, is an informal gathering of players who share a common repertoire of traditional Irish tunes. They enjoy a symbiotic relationship with the bars that host them — the musicians provide the atmosphere, and the pub becomes their second home.

The Green Briar, a beloved Irish bar in Brighton, is host to what may be the longest-running session in Boston. Every Monday night for the past 29 years, musicians of all ages and abilities have descended upon the bar, filling up its big back room for a massively popular, beginner-friendly session in the early part of the evening, followed by a more experienced (read: faster) session that lasts into the wee hours of the night. As the Green Briar prepares to close its doors for good on May 6, its beloved Monday night session faces an uncertain future.

I visited the second-to-last Green Briar session — click the red player button atop this post to hear sounds from that night, and scroll below to check out the scene:

Players join in the Irish music session at the Green Briar pub in Brighton on a recent Monday night. (Hadley Green for WBUR)

Green Briar boasts one of the longest-running Irish sessions in Boston. (Hadley Green for WBUR)

Leslie Kurtzberg, left, plays a penny whistle during the early session. (Hadley Green for WBUR)

Monday night at Green Briar is packed with people of all ages and experience levels joining into the session. (Hadley Green for WBUR)

Barry Shapiro plays a piano accordion at the Green Briar. (Hadley Green for WBUR)

Theresa Stokinger, 8, plays the fiddle at the Green Briar. (Hadley Green for WBUR)

Leslie Kurtzberg plays a penny whistle. (Hadley Green for WBUR)

John O'Sullivan listens to music being played at the Green Briar pub. (Hadley Green for WBUR)

Barry Shapiro plays a piano accordion during an Irish music session at the Green Briar pub in Brighton. (Hadley Green for WBUR)

Bill Perry on the mandolin. (Hadley Green for WBUR)