During the summer, the National Mall hums at night with the sounds of free concerts and events. Locals bring lawn chairs, coolers, and such, but all you really need is a hotel blanket and a picnic from a local deli to make a memory.
The U.S. Capitol ’s West Front hosts free military-band concerts during the summer at 8 p.m.: the Navy Band plays Mondays, the Air Force Band on Tuesdays, the Marine Corps Band on Wednesdays, and the Army Band on Fridays.
If you’re at the Mall on Thursday, head to the grounds of the Washington Monument , where you’ll find the Marine Band performing at 8 p.m.
The National Art Gallery  also hosts a summer music series, jazz in its sculpture garden every Friday 5-8:30 p.m. Bring your own picnic or pick one up at the Pavilion Café in the garden, but get there early for good seats; this event is a Washington after-work favorite.
The outdoor film series Screen on the Green takes place on the National Mall between 4th Street and 7th Street NW on Mondays during the summer and features classic movies under the stars. Past screenings have included Twelve Angry Men and Goldfinger. Bring a picnic, bug spray, and a blanket or one of those short beach chairs, and plan to arrive by 7 p.m. for a decent seat. (The movie starts when it’s nearly dark, around 9 p.m.)
The biggest event on the Mall during the summer is the July 4 concert and fireworks, but locals head to the U.S. Capitol ’s West Front on July 3 for the dress rehearsal, which usually starts around 7:30 p.m. The event is not exactly a secret, and the closest lawn spaces fill quickly, but the crowds are nowhere near the size they’ll be the following day. Also, don’t expect to see everyone who’s scheduled; some performers, like the Beach Boys a few years back, skip the rehearsal.