Antonius da Civitate Austrie, also known as Cividal, Civitato, and Antonio da Cividale, was a Northern Italian monk of the Dominican order whose name suggests he was appointed to the council of the Cividale by Pope Gregory XII in 1410. He may have been born in the lands administered by the early Hapsburg Empire, but was nonetheless Italian, and his entire known musical career was spent in the service of papal courts in Venice and Florence. Antonius is first heard from through his arrival in Venice in 1392 to join the Dominican monastery there. Antonius' presence in Florence by the year 1414 is noted through his motet O felix flos Florencia/Gaude felix Dominice. It is not known if he participated in the Council of Constance that ended the "great schism" and established Martin V as pope. But the four-voice motet Clarus ortus clariore opera/Gloriosa mater ecclesia celebrates the long-delayed return of the pope to his papal throne in Rome, a ceremony held on September 28, 1420. Although works of Antonius da Civitate Austrie continue to appear in manuscripts compiled through the 1430s, he is not heard from again after Martin V was installed in Rome; perhaps he perished in the outbreak of Black Plague that struck Italy in 1423. Antonius was an important composer of isorhythmic motets and was intimately familiar with French style, also composing ballades, rondeaux, and virelai. His three-voice ballade Vous soyes si las venus contains a part that is a palindromic "loop" that repeats forwards and backwards for the entire composition. Three sacred works of Antonius are likewise known, including a paired Gloria and Credo. All of these benefit from structural practices that are derived from secular composition.