LENOX — In order for the Boston Symphony Orchestra to participate in the numerous European music festivals that take place over the summer, the orchestra has to leave before the last weekend of the Tanglewood Music Festival.

This year, the BSO's European tour, its first since 2018, includes festivals in London and Paris, in Hamburg and Berlin, in Salzburg, and in Slovenia and Switzerland. In the past, the last weekend has featured visiting orchestras and visiting conductors or, less effectively, chamber music — originally designed for small 19th-century salons — in the vastness of the Koussevitzky Music Shed. The only way the latter tactic can work, in terms of filling enough seats, is by programming international superstars of classical music, such as Yo-Yo Ma and Emanuel Ax.

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On Friday, Aug. 25, are Leonidas Kavakos, violin, Ma, cello, and Ax, piano, performing an all-Beethoven program. BSO officials have confirmed Ma will perform, as the famous cellist has recovered from COVID. On the docket are a transcription of Beethoven's Symphony. No. 4 and the original Piano Trio No. 7, in B flat, Opus 97, subtitled "The Archduke,' because it was dedicated to Archduke Rudolf of Austria, the youngest brother of the emperor and both a pupil and a patron of the composer. Rudolf was the recipient of many dedications by Beethoven; he was the composer’s staunchest advocate and his most generous patron.

The Trio, Op. 97, is a magnificent work, broad in scope and deep in expression. The piano role is extensive, though both strings contribute strongly to the overall effect. The work was completed in 1811, but the first public performance, with Beethoven at the piano, was not until 1814. By this time Beethoven was tragically experiencing the most profound ravages of the deafness that would blight the rest of his life, and his piano playing, once the wonder of Vienna, had deteriorated to a devastating degree. An auditor wrote sadly of witnessing the rehearsal, when “in loud passages the poor deaf man pounded on the keys until the strings jangled, and in soft passages, he played so softly that whole groups of notes were omitted.” After this, Beethoven never again played in public.

Let us put ourselves back into early 19th-century Vienna, when new works by some of the most renowned composers were appearing regularly on the scene. How would one hear them? Performances by full orchestras were rare. Publishers therefore took advantage of the amateur music world and published orchestral works in arrangements for a small number of instruments, to be played in small halls and salons by amateurs throughout the region.

In addition to the “Archduke” Trio, Friday's program includes an arrangement of Beethoven’s Fourth Symphony for piano trio (piano, violin, and cello). The arrangement captures the essence of the work, though not, of course, its color, scope, or grandeur.

Of special note, is Friday's Prelude Concert, 6 p.m., Seiji Ozawa Hall featuring the Kids 4 Harmony, a free, intensive classical music program serving youth attending Pittsfield's Morningside Community School and Brayton Elementary School in North Adams. Performing during the prelude concert are the North Adams and Pittsfield Advanced String Ensemble, the Elayne P. Bernstein Ensemble and the Kids 4 Harmony Chamber Players. For the last piece of the concert, The Kids 4 Harmony Chamber Players will play the last movement of Mozart’s Piano Quartet No. 1. They'll be joined by a special guest — Ax, who also is one of their their strongest supporters.

'HARRY POTTER' AND 'STAR WARS'

On Saturday, Aug. 26, the Boston Pops Esplanade Orchestra plays along to the film “Harry Potter and the Sorcerer’s Stone," with an open rehearsal at 10:30 a.m. (gates open at 9 a.m.), followed by an 8 p.m. performance (gates open at 5:30 p.m.). On Sunday, Aug. 27, 2:30 p.m., the Boston Pops Esplanade Orchestra performs "Star Wars: The Story in Music," an immersive musical journey through all nine movies of the "Star Wars" saga in just two hours.

TANGLEWOOD POPULAR ARTISTS SERIES

Rounding out this season art the final three Tanglewood Popular Artists Series Concerts: Jackson Browne, 7 p.m., Aug. 31; Guster, 7 p.m. Sept. 2; and John Legend, 7 p.m. Sept. 3.