13 historic monuments, puzzles which are still not solved

3. Newgrange, Ireland

In the 17th century, road builders unexpectedly stumbled upon an extraordinary monument, yet it wasn't until nearly three hundred years later that thorough research commenced.

The excavations unveiled a perfectly round mound with an impressive diameter, predating the Egyptian pyramids. At its center, archaeologists discovered a tomb.

If you're fortunate enough to visit during the solstice, you'll witness a breathtaking celestial phenomenon as a ray of light gradually illuminates the entire chamber. Local Irish folklore suggests that this enchanting place serves as a gateway to the realm of elves and fairies.