Year 1503 (MDIII) was a common year starting on Sunday (link will display the full calendar) of the Julian calendar. Events January–June January 20 – Seville in Castile is awarded exclusive rights to trade with the New World. January 24 – Construction of the Henry VII Chapel at Westminster Abbey begins in the perpendicular style, the final stage of English Gothic art. February 13 – Challenge of Barletta: Thirteen Italian knights defeat thirteen French knights, near Barletta. February 23 – French–Spanish Wars in Italy – Battle of Ruvo: The Spanish defeat the French. April 21 – Battle of Seminara: Spanish forces under Fernando de Andrade de las Mariñas defeat the French under Bernard Stewart, 4th Lord of Aubigny. April 21 – Battle of Cerignola: Spanish forces under Gonzalo Fernández de Córdoba defeat the French under Louis d'Armagnac, Duke of Nemours, who is killed (considered to be the first battle in history won by gunpowder small arms). May 10 – Christopher Columbus discovers the Cayman Islands, which he names Las Tortugas, after the numerous sea turtles there. May 13 – Naples is captured by the Spanish. May 20 (Feast of the Ascension) – Ascension Island is first definitively sighted, by Portuguese admiral Afonso de Albuquerque. May 28 – James IV of Scotland and Margaret Tudor are married as per the Treaty of Perpetual Peace by Pope Alexander VI, according to Papal bull. July–December July 23 – Orbital calculations suggest that on this day, Pluto moved outside Neptune's orbit, remaining there for 233 years. July 30 – Saint Helena is first definitively sighted, by ships of Portuguese navigator Estêvão da Gama returning from the East. August 8 – King James IV of Scotland marries Margaret Tudor, daughter of King Henry VII of England, at Holyrood Abbey, Edinburgh, Scotland. August 20 – Stephen III of Moldavia concludes a treaty with Sultan Bayezid II, preserving Moldavia's self-rule at the cost of an annual tribute to the Ottoman Empire. September 22 – Pope Pius III (Francesco Todeschini Piccolomini) succeeds Alexander VI as the 215th pope, but dies on October 18. October 30 – Queen Isabella I of Spain prohibits violence against indigenous peoples in the New World. October 31 – Pope Julius II succeeds Pius III, as the 216th pope (some sources list November 1 as the date of election). December 29 – Battle of Garigliano, near Gaeta, Italy: Spanish forces under Gonzalo Fernández de