CAMBRIDGE — There is a damp dustiness down here, in the abandoned tunnel underneath Harvard Square. Aside from the thin rays filtering through a sidewalk grate, there isn’t much light where we’re standing, 20 feet below the beer taps of Charlie’s Kitchen and the Harvard grads snapping pictures in front of the Kennedy School of […] The post Inside the hidden tunnel under Harvard Square that could be the region’s coolest music venue appeared first on Boston.com.