Foursquare Magisterium Rum 16 years, XXVIMagisterium is a blend of three distinct 16 year Single Blended Rums, distilled in the copper Double Retort Pot Still and the Continuous Twin Column Coffey Still of Foursquare. Two of the rums were double maturations, one aging three years in ex Bourbon casks, then 13 additional years in Ex Oloroso Sherry Barrels; the other aging nine years in Ex Bourbon followed by seven years in Ex Oloroso Sherry. The last was a Single Blended Rum matured entirely