A Scottish church which featured in the best-selling novel "The Da Vinci Code" has revealed another mystery hidden in secret code for almost 600 years.
A father and son who became fascinated by symbols carved into the chapel's arches say they have deciphered a musical score encrypted in them.
Thomas Mitchell, a 75-year-old musician and ex-Royal Air Force code breaker, and his composer and pianist son Stuart, described the piece as "frozen music."
"The music has been frozen in time by symbolism," Mitchell said on his Web site (www.tjmitchell.com/stuart/rosslyn.html), which details the 27-year project to crack the chapel's code.
"It was only a matter of time before the symbolism began to thaw out and begin to make sense to scientific and musical perception."
The 15th Century Rosslyn Chapel, about seven miles south of the Scottish capital Edinburgh, featured in the last part of Dan Brown's "The Da Vinci Code" -- one of the most successful novels of all time which has been turned into a Hollywood film.
Stuart Mitchell said he and his father were intrigued by 13 intricately carved angel musicians on the arches of the chapel and by 213 carved cubes depicting geometric-type patterns.
"They are of such exquisite detail and so beautiful that we thought there must be a message here," he told Reuters.
Years of research led the Mitchells to an ancient musical system called cymatics, or Chladni patterns, which are formed by sound waves at specific pitches.
The two men matched each of the patterns on the carved cubes to a Chladni pitch, and were able finally to unlock the melody.
The Mitchells have called the piece The Rosslyn Motet and added words from a contemporary hymn to complete it.
They have also scheduled a world premiere at a concert in the chapel on May 18, when four singers will be accompanied by eight musicians playing the piece on medieval instruments.
Simon Beattie of the Rosslyn Chapel Trust said he was delighted to have the mystery finally solved, and was intrigued by the music itself.
"It's not something you would want to put on in the car and listen to, but it's certainly an interesting piece of music," he said. "It's got a good medieval sound to it."