Bargemusic
Visitor Center at the Boathouse, Brooklyn Bridge Park
Free chamber music every Saturday and Sunday at 2 PM, an hour to an hour and a half, no tickets or reservations. The barge itself is retired for now, so concerts are on land; doors open 20 minutes before.
Manhattan School of Music student recitals
130 Claremont Ave, Morningside Heights
Hundreds of student recitals a year, free and open to everyone. Some of the best young players in the city.
Juilliard
Lincoln Center
Many performances are free. Some need a free ticket booked online, others are first come, first served; there is no standby line, so check for released tickets.
Trinity Wall Street, Wednesdays at 1
Trinity Church, Financial District
Free lunchtime concerts most Wednesdays at 1 PM, including Bach at One.
Midtown Concerts
St. Malachy’s, 239 W 49th St, Theater District
Free early-music and chamber concerts on Thursdays at 1:15 PM, from September to June.
Music Mondays
Advent Lutheran Church, Broadway at 93rd St
Free Monday-evening chamber concerts several times a season.