By L. L. Zamenhof (lyrics) and Félicien Menu de Ménil (composition).

Listen on YouTube.

Read artist commentary.

Tracks that reference La Espero:

From Beyond:

• Malblanka Rozo Verda Stelo by jan Misali

Lyrics:

En la mondon venis nova sento (Into the world came a new feeling)
Tra la mondo iras forta voko (Through the world goes a powerful call)
Per flugiloj de facila vento (By means of wings of a gentle wind)
Nun de loko flugu ĝi al loko (Now let it fly from place to place)

Ne al glavo sangon soifanta (Not to a bloodthirsty sword)
Ĝi la homan tiras familion (Does it draw the human family)
Al la mond' eterne militanta (To the eternally fighting world)
Ĝi promesas sanktan harmonion (It promises sacred harmony)

Sub la sankta signo de l' espero (Under the sacred sign of the hope)
Kolektiĝas pacaj batalantoj (The peaceful fighters gather)
Kaj rapide kreskas la afero (And this affair quickly grows)
Per laboro de la esperantoj (By the labours of those who hope)

Forte staras muroj de miljaroj (Walls of millennia stand firmly)
Inter la popoloj dividitaj (Between the divided people)
Sed dissaltos la obstinaj baroj (But the stubborn barriers will jump apart)
Per la sankta amo disbatitaj (Knocked apart by the sacred love)

Sur neŭtrala lingva fundamento (On a neutral language basis)
Komprenante unu la alian (Understanding one another)
La popoloj faros en konsento (The people will make in agreement)
Unu grandan rondon familian (One great family circle)

Nia diligenta kolegaro (Our diligent set of colleagues)
En laboro paca ne laciĝos (In peaceful labor will never tire)
Ĝis la bela sonĝo de l' homaro (Until the beautiful dream of humanity)
Por eterna ben' efektiviĝos (For eternal blessing is realized)

Artist commentary:

Niklink: (wiki editor)

While Félicien Menu de Ménil's composition is by far the best known, there are several other tunes created for it that date much earlier. Translated lyrics via Wikipedia.