- The school was founded in 1933 on the site of the 19th-century County Gaol, the old boundary walls of which surround the school.
- The crest is based on the supposed badge of John de Courcy, the Norman knight who captured Downpatrick in 1177 and established himself as ruler of northeast Ulster.
- The twin mottos are Floreat Dunum (May Down flourish) and Absque labore nihil (Nothing achieved without effort).
- Since 2015 the school has won the Eco-Schools Green Flag annual accreditation for its environmental awareness.
- The rock band Ash rose to fame in the early 1990s while its three members were attending Down High School.
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