Merriweather Post Pavilion sits in a wooded park between Baltimore and Washington DC, which means it draws from two cities and somehow feels like neither of them. The covered pavilion holds about 19,000 people between the reserved seats and the lawn, and the lawn is the point — a wide, sloping hill of grass where people spread out and the sound travels up through the trees. It opened in 1967, named after Marjorie Merriweather Post, and it has hosted nearly every major act in American music since. Dave Matthews built a career playing this lawn. Phish comes back regularly. The surrounding woods dampen the outside world in a way that indoor venues never manage. The nearest major airports are BWI (21 miles), DCA (32 miles), and IAD (38 miles). Park early. The lot situation is serious.