Somewhat cavernous on a random weeknight, The Eagle is great for punk shows and karaoke, but best for the Sunday beer bust, that raucous weekly benefit where $15 gets you barbecue and all the Miller Lite you can drink in the company of muscle daddies and wonderful weirdos. Along with Eagle Plaza, the centerpiece of the burgeoning Leather and LGBT Cultural District, the bar’s impending landmark designation shows that City Hall understands what it’s got here: a civic treasure.