When we get to the busiest part of the classical music season, there is at least one worthy event, sometimes more than one, for every night of the week. No one is complaining, since we like to have concerts to hear, but it does require careful scheduling.

WEDNESDAY:
>> There is no question that, this Wednesday evening (February 21, 8 p.m.), the hottest classical ticket will be a free one. The Venice Baroque Orchestra, directed by Andrea Marcon, will play behind violinist Giuliano Carmignola in a free concert at the Library of Congress. The program is almost entirely devoted to the music of Vivaldi (their recordings of the Red Priest have been warmly received), with one piece by Tartini. If you are not lucky enough to have a reserved ticket, show up as early as possible to line up for an unused seat.

THURSDAY:
>> The following night (February 22, 8 p.m.), it is the concert offered by the Baltimore Symphony Orchestra, in the Music Center at Strathmore. Incoming music director Marin Alsop has put together a program to honor the 70th birthday of American composer Philip Glass this year, beginning with the Concerto for Saxophone Quartet. The group will also give the world premiere of LIFE: A Journey Through Time, a new score by Glass that accompanies photographs by National Geographic photographer Frans Lanting. Limited tickets remain at the time of this writing.

>> The same night (February 22, 7 p.m.), the National Symphony Orchestra begins its three-night series of concerts in the Kennedy Center Concert Hall. Violinist Janine Jansen will make her first appearance with the NSO, playing the celebrated violin concerto by Felix Mendelssohn. Her new recording of the Mendelssohn (and Bruch) concerto, with the Leipzig Gewandhaus Orchestra, is good. (Also February 23 and 24.)

FRIDAY:
>> To start your weekend (February 23, 8 p.m.), it is back to the Library of Congress for another free concert of 18th-century music. Marc Hantaï (flute), Alessandro Moccia (violin), Alix Verzier (cello), and Jérôme Hantaï (fortepiano) will play pieces by J. C. Bach, Haydn, and Mozart.