Our votes on the 58th tier selected the following works...
To move up 2 to the 56th tier:
Hildegard von Bingen: Symphonia Armonie Celestium Revelationum [12th century]
To move up 1 to the 57th tier:
Bach: Cantata #56 "Ich will den Kreuzstab gerne tragen" [1726]
Berg: Lulu [1935]
Enescu: Piano Quintet, op. 29 [1940]
Falla: El Sombrero de Tres Picos (The Three-Cornered Hat)
Grisey: Les Espaces acoustiques [1985]
Haydn: The Seven Last Words of Christ, Hob. XX/1a [1786]
Machaut: Songs from Le Voir-Dit, including "Puis qu'en oubli" [mid-14th century]
Mozart: Piano Sonata #14 in C minor, K. 457 [1784]
Nancarrow: Studies for Player Piano [1948-1992]
Pachelbel: Canon and Gigue in D [c. 1700]
Penderecki: St. Luke Passion [1966]
Schoenberg: Pieces (5) for Orchestra, op. 16 [1909]
Shostakovich: Lady Macbeth of the Mtsensk District, op. 29 [1934]
Strauss, R.: Don Juan, op. 20 [1888]
Victoria: Tenebrae Responsories [1585]
Webern: Im Sommerwind [1904]
To remain on the 58th tier:
Babbitt: All Set [1957]
Bach: Concerto for Two Harpsichords in C minor, BWV 1060 [c. 1736]
Bruch: Symphony #3 in E, op. 51 [1884]
Donizetti: La fille du régiment [1840]
Elgar: Violin Concerto in B minor, op. 61 [1910]
Feldman: Piano and String Quartet [1985]
Hahn: Chansons grises (7) [1890]
Hanson: Symphony #2 in D-flat, op. 30 "Romantic" [1930]
Haydn: Andante with Variations in F minor, Hob. XVII/6 "Un piccolo divertimento" [1793]
Haydn: Piano Sonata #31 in A-flat, Hob. XVI/46 [1770]
Haydn: Symphony #84 in E-flat ("In nomine Domini") [1786]
Haydn: Symphony #87 in A [1786]
Ives: A Symphony: New England Holidays [1913]
Lekeu: Violin Sonata in G [1892]
Mozart: Symphony #31 in D, K. 297 "Paris" [1778]
Rochberg: String Quartet #3 [1971]
Ropartz: Prélude, Marine et Chansons [1928]
Saariaho: L'Amour de loin [2000]
Saint-Saëns: Samson et Dalila, op. 47 [1877]
Scarlatti, D.: Keyboard Sonata in F minor, K. 466 [18th cent.]
Schoenberg: Gurrelieder [1910]
Scriabin: Symphony #3 in C minor, op. 43 "Le Divin Poème" [1904]
Taverner: Missa Gloria tibi Trinitas [probably 1526-1530]
Varèse: Déserts [1954]
Vaughan Williams: English Folk Song Suite [1923]
Villa-Lobos: Etudes (12) [1953]
Weber: Clarinet Concerto #2 in E-flat, op. 74 [1811]
Wieniawski: Violin Concerto #2 in D minor, op. 22 [1862]
To move down 1 to the 59th tier:
Schubert: Symphony #3 in D, D. 200 [1815]