One of these mysterious portals is Rosslyn Chapel on a Scottish estate within the Falkirk Triangle.

“It was founded in 1446 by a nobleman who wanted it to be a place where priests could pray for his family souls,” explains archeologist Natasha. "From the outside it looks like a small stone church, but inside it is extraordinary.

“Every inch of the walls and ceilings is covered in intricate stone carvings. Stars, flowers, vines, angels playing instruments, and grotesque gargoyles. The most famous carving is The Apprentice’s Pillar, which is a twisted vine-like design which some think looks like a DNA helix.”

The tiny chapel appeared in Dan Brown’s The Da Vinci Code, and theorists believe there are engravings of sweetcorn and aloe vera, which were carved long before Christopher Columbus went to the New World and brought those plants back - adding to theories that this is the work of people who had encountered aliens.

“One of the most striking things you see in the ceiling are these carved blocks in rows,” explains Tony. "One theory is that they are musical notes. By deciphering them you can play a piece of music. This represents an understanding of acoustics that was way ahead of the time the chapel was built.

“For people to have known that, they would have had to be informed by somebody with future knowledge.”