The most fascinating stories about Rosslyn Chapel tell of treasure of some kind being hidden there. A crypt has been found with the same depth and height as that of the Chapel, but is accessible at the moment only by a very old staircase and it is filled with fine sand. William Saint Clair (“the Seemly”) brought from the Holy Land the “Holy” or “Blood Rood” which is purportedly part of the true cross and satu­rated with Christ’s blood. This is the relic after which Holyrood House and Abbey were named.
” The incident is apparently quite reliably reported. The member of the family who was killed was on active service in the RAF (the British Royal Air Force).
Rosslyn Chapel

The Holy Rood and the Stone of Scone are considered to be the most valuable artifacts among the Scottish coronation treasures. Sir William Sinclair saved many of the Scottish treasures during the Reformation and it is thought that he hid them at Rosslyn Chapel. If this is the case, it is more than likely that they are still in the crypt today. Additionally, some of the Templar treasure which was brought from France to Scotland during the Catholic Inquisition is thought to be contained within this crypt. It may also be home to the scrolls of the Zadok priests of first century Jerusalem. This is perhaps the most valuable type of treasure that Rosslyn Chapel could conceivably reveal to us. Perhaps this is what Sir William Sinclair was referring to when he inscribed the following in Latin on a lintel next to the Apprentice Pillar:
“Wine is strong, a_ King is stronger, women are even stronger, but TRQTH conquers all.”