Year 504 (DIV) was a leap year starting on Thursday of the Julian calendar. At the time, it was known as the Year of the Consulship of Nicomachus without colleague (or, less frequently, year 1257 Ab urbe condita). The denomination 504 for this year has been used since the early medieval period, when the Anno Domini calendar era became the prevalent method in Europe for naming years.

• War with Sassanid Persia: Emperor Anastasius I gains the upper hand in Armenia, with the renewed investment of Amida.
• King Kavadh I hands over the fortress-city of Amida, and agrees to an armistice with the Byzantine Empire.

• King Theodoric the Great defeats the Gepids, and drives them out of their homeland (Pannonia).^[1]
• The Ostrogoths sack Belgrade, on the Danube and Sava rivers (modern Serbia).

• A major expansion of Copán's ceremonial center, the Acropolis complex, is undertaken by B'alam Nehn (Waterlily Jaguar), the seventh ruler (ajaw) of the southeastern Maya city (approximate date).

• Theodoric the Great builds the Basilica of Sant'Apollinare Nuovo, originally dedicated to Christ the Redeemer.

• Muyal Jol, ruler of Copan