Sgt. Pepper presumably thought two decades was a long time when he made a big deal out of announcing it'd been "20 years ago" since he started his band.

Twenty years?! That's nothing!

It's been about twice that long since New London's justifiably famous music scene exploded — as properly documented on the "Towers of New London" album compilations. Indeed, looking back, for those who in fact have lived long enough to "look back" 40 years, those were some magical musical times for NL bands.

In proper commemoration, several of those artists gather Friday night in the Hygienic Art Park for an unplugged evening celebrating new and old tunes. Taking part are Hugh Birdsall, the New Johnny 5, Vacant Lot, Clothespins, the Whales (in a poignant appearance following the loss of guitarist Eddie Sabukewicz), Blonde Furniture, The Motive 8 and Stark Weather.

Towers of New London Unplugged, 6-10 p.m. Friday, Hygienic Art Park, 79 Bank St., New London; $20; hygienic.org.