Ein' feste Burg usw.

Ein' feste Burg ist unser Gott is Martin Luther's most famous hymn, the "national anthem" of Lutheranism but also widely popular in other denominations.

Ein' feste Burg ist unser Gott — German original by Martin Luther, c. 1529
A mighty fortress is our God — English version by Frederick H. Hedge (the usual traditional version in the United States)
A safe stronghold our God is still — English version by Thomas Carlyle (older traditional version in the United Kingdom)

Two Esperanto versions:

• Anonymous;
• translated (vv. 1-3) by H. A. de Hoog (v. 4, anonymous)
  The Cyber Hymnal™ has an additional English version, and also translations in French, Malayalam, Portuguese, and Spanish.
  
  The tune, called EIN' FESTE BURG, is also credited to Martin Luther; it exists in two versions, "rhythmic" and "isorhythmic" or "isometric".