
The Art of Fugue, or The Art of the Fugue, BWV 1080, is an incomplete musical work of unspecified instrumentation by Johann Sebastian Bach. Written in the last decade of his life, The Art of Fugue is the culmination of Bach's experimentation with monothematic instrumental works.

The Viola Concerto in A minor, Sz. 120, BB 128 was one of the last pieces written by Béla Bartók. He began composing his viola concerto while living in Saranac Lake, New York, in July 1945. The piece was commissioned by William Primrose, a respected violist who knew that Bartók could provide a challenging piece for him to perform. He said that Bartók should not "feel in any way proscribed by the apparent technical limitations of the instrument"; Bartók, though, was suffering from the terminal stages of leukemia when he began writing the viola concerto and left only sketches at the time of his death.

Lulu is an opera in three acts by Alban Berg. Berg adapted the libretto from Frank Wedekind's two Lulu plays, Erdgeist and Die Büchse der Pandora.

Messe solennelle is a setting of the Catholic Solemn Mass by the French composer Hector Berlioz. It was written in 1824, when the composer was twenty and first performed at the Church of Saint-Roch in Paris on 10 July 1825, and again at the Church of Saint-Eustache in 1827. After this, Berlioz claimed to have destroyed the entire score, except for the "Resurrexit", but in 1991 a Belgian schoolteacher, Frans Moors, came across a copy of the work in an organ gallery in Antwerp and it has since been revived.

The Symphony in C is an early work by the French composer Georges Bizet. According to Grove's Dictionary, the symphony "reveals an extraordinarily accomplished talent for a 17-year-old student, in melodic invention, thematic handling and orchestration." Bizet started work on the symphony on 29 October 1855, four days after turning 17, and finished it roughly a month later. It was written while he was studying at the Paris Conservatoire under the composer Charles Gounod, and was evidently a student assignment. Bizet showed no apparent interest in having it performed or published, and the piece was never played in his lifetime. He used certain material from the symphony in later works, however. There is no mention of the work in Bizet's letters, and it was unknown to his earlier biographers. His widow, Geneviève Halévy (1849–1926), gave the manuscript to Reynaldo Hahn, who passed it along with other papers to the archives of the conservatory library, where it was found in 1933 by Jean Chantavoine. Soon thereafter, Bizet's first British biographer Douglas Charles Parker (1885–1970) showed the manuscript to the conductor Felix Weingartner, who led the first performance in Basel, Switzerland, on 26 February 1935.

Prince Igor is an opera in four acts with a prologue, written and composed by Alexander Borodin. The composer adapted the libretto from the Ancient Russian epic The Lay of Igor's Host, which recounts the campaign of Rus' prince Igor Svyatoslavich against the invading Cuman ("Polovtsian") tribes in 1185. He also incorporated material drawn from two medieval Kievan chronicles. The opera was left unfinished upon the composer's death in 1887 and was edited and completed by Nikolai Rimsky-Korsakov and Alexander Glazunov. It was first performed in St. Petersburg, Russia, in 1890.

The String Quartet in C minor WAB 111, was composed by Anton Bruckner's in 1862 during his tuition by Otto Kitzler.

The Symphony No. 9 in D minor, WAB 109, is the last symphony on which Anton Bruckner worked, leaving the last movement incomplete at the time of his death in 1896; Bruckner dedicated it "to the beloved God". The symphony was premiered under Ferdinand Löwe in Vienna in 1903.

Koanga is an opera written between 1896 and 1897, with music by Frederick Delius and a libretto by Charles Francis Keary, inspired partly by the book The Grandissimes: A Story of Creole Life by George Washington Cable (1880). Inspiration also came from Delius's own experiences as a young man, when his family sent him to work in Florida. It was Delius's third opera, and he thought better of it than of its predecessors, Irmelin and The Magic Fountain, because of the incorporation of dance scenes and his treatment of the choruses. Koanga is reputed to be the first opera in the European tradition to base much of its melodic material on African-American music.

The Symphony No. 3 in E♭ major, Op. 10, B. 34 is a classical composition by Czech composer Antonín Dvořák.

The String Quartet in E minor, Op. 121, is the only string quartet by Gabriel Fauré. Completed in 1924 shortly before his death at the age of 79, it is his last composition. His pupil Maurice Ravel had dedicated his String Quartet to Fauré in 1903, and he and others urged Fauré to compose one of his own; he declined, on the grounds that it was too difficult. When he finally decided to write it, he did so in trepidation.

The Symphony No. 10 in F-sharp major by Gustav Mahler was written in the summer of 1910, and was his final composition. At the time of Mahler's death, the composition was substantially complete in the form of a continuous draft, but not fully elaborated or orchestrated, and thus not performable. Only the first movement is regarded as reasonably complete and performable as Mahler intended. Perhaps as a reflection of the inner turmoil he was undergoing at the time, the 10th Symphony is arguably his most dissonant work.

Pictures at an Exhibition is a suite of ten pieces—plus a recurring, varied Promenade—composed for piano by Russian composer Modest Mussorgsky in 1874.

Giacomo Puccini's Messa or Messa a quattro voci is a Mass composed for orchestra and four-part choir with tenor and baritone soloists. Strictly speaking, the piece is a full Mass, not a true Messa di Gloria.

Turandot is an opera in three acts by Giacomo Puccini, posthumously completed by Franco Alfano in 1926, and set to a libretto in Italian by Giuseppe Adami and Renato Simoni. Its best-known aria is "Nessun dorma".

Russian composer Sergei Rachmaninoff's Symphony No. 1 in D minor, his Op. 13, was composed between January and October 1895 at his Ivanovka estate near Tambov, Russia. Despite its poor initial reception, the symphony is now seen as a dynamic representation of the Russian symphonic tradition, with British composer Robert Simpson calling it "a powerful work in its own right, stemming from Borodin and Tchaikovsky, but convinced, individual, finely constructed, and achieving a genuinely tragic and heroic expression that stands far above the pathos of his later music."

The Youth Symphony in D minor is the first movement of a symphony written by Sergei Rachmaninoff, the score of which is dated September 28, 1891. It is the only movement of the work that was completed.

The Carnival of the Animals is a humorous musical suite of fourteen movements by the French composer Camille Saint-Saëns. The work, about 25 minutes in duration, was written for private performance by two pianos and chamber ensemble; Saint-Saëns prohibited public performance of the work during his lifetime, feeling that its frivolity would damage his standing as a serious composer. The suite was published in 1922, the year after his death. A public performance in the same year was greeted with enthusiasm, and the work has remained among his most popular. In addition to the original version for chamber ensemble, the suite is frequently performed with a full orchestral complement of strings.

Jack in the Box is a work written by Erik Satie in 1899 for a pantomime-ballet to a scenario by the illustrator Jules Depaquit. Satie gave it an English title because English phrases were considered fashionable in Parisian society at the time.

Robert Schumann's Violin Concerto in D minor, WoO 23, written in 1853, was his only violin concerto and one of his last significant compositions. It remained unknown to all but a very small circle for more than 80 years after it was written.

Charles Villiers Stanford's Violin Sonata No. 2 in A major, Op. 70, was composed around 1898. Performed only once during the composer's lifetime, the sonata remained unpublished until 2006.

The Emerald Isle; or, The Caves of Carrig-Cleena, is a two-act comic opera, with music by Arthur Sullivan and Edward German, and a libretto by Basil Hood. The plot concerns the efforts of an Irish patriot to resist the oppressive "re-education" programme of the English, which has robbed the Irish of their cultural heritage. A quirky "Professor of Elocution" who is hired by the English to continue this "re-education" of the Irish switches sides to help the Irish defend their culture. Romantic complications cause a confrontation between the Irish patriots and the superstitious English at the supposedly haunted caves of Carric-Cleena, and disguises are employed to hold the English off; but the professor ultimately comes up with a solution that works out happily for all.