title: 285 BC
text: 
  Year 285 BC was a year of the pre-Julian Roman calendar.
  
  Events
  
  By place
  
  Egypt 
   June 26 – Egypt's Ptolemy I Soter quits ruling. He is succeeded by his youngest son by his wife Berenice, Ptolemy II Philadelphus.  He was co-regent for three years.
   A 110 metre tall lighthouse on the island of Pharos in Alexandria's harbour is completed.  It is a landmark for ships in the eastern Mediterranean. Built by Sostratus of Cnidus for Ptolemy II of Egypt, it is one of the seven wonders of the ancient world. It is a technological triumph and is the archetype of all lighthouses since. A broad spiral ramp leads to the top, where a fire burns at night.
  
  Seleucid Empire 
   Demetrius Poliorcetes is left by his troops and surrenders to Seleucus at Cilicia, where Seleucus keeps him a prisoner.
  
  Deaths 
  
   Dicaearchus, Greek philosopher, cartographer, geographer, mathematician and author (b. c. 350 BC)
  
  280s BC