According to Official Guinness Records,
The oldest known rum is The Harewood Rum 1780, believed to have been distilled in 1780 in Barbados. In 2011, fifty-nine bottles of the previously-forgotten rum were discovered in the basement of Harewood House, Leeds, UK. The rum was distilled in Barbados, but in the early 19th century it was shipped to the UK and bottled at by Oldfield’s of York at the request of Edward Lascelles, the first Earl of Harewood. In 2011, Mark Lascelles and Andy Langshaw discovered fifty-nine bottles of the rum in the basement of Harewood House. Twenty-eight of the bottles were a dark rum, and the other thirty-one were a light rum. In 2013, twelve of these bottles were put up for sale and were purchased by a range of customers including Wealth Solutions (Poland), who purchased a bottle of the light rum. Together with Speake-Marin, a Swiss watch manufacturer, Wealth Solutions created a range of 59 watches, each containing a single drop of the rare spirit.
For a complete list of 1780 records, please visit 1780 Guinness Records in United Kingdom.