While this "magic door" is famous to Romans, it is barely noticed by tourists visiting Rome. But in the central district of Piazza Vittorio, inside the park, the remains of an old villa reveal a Magic or Alchemist Door, a portal into the real and secretive world of 1600s alchemy.

Full of symbols and inscriptions, it was built during the early 1600s by the Roman marquis Massimiliano Palombara, a member of a group of people known as "The Alchemists of Palazzo Riario" who congregated around the Roman court of Christina, the Queen Regent of Sweden. Christina was an ardent supporter of alchemy and science, and thinkers and science luminaries like Rene Descartes and Athanasius Kircher were often found in her Italian court along with alchemy enthusiasts like Palombara.

The Porta Alchemica is the only remaining of five doors to Palombara's villa. According to legend, the Marquis met an alchemist at a dinner party who told him he could use a certain herb to turn metals to gold. In the morning the alchemist (said to be Giuseppe Francesco Borri, a sort of alchemical Zelig) was gone but had left behind some gold flakes, evidence apparently of his successful transformations, and an indecipherable sheet, the "recipe" for the transformation. Because the Marquis was unable to read it he inscribed the recipe on his doors in the hope that someone who could understand it would see it and come knocking.

Mystery and occult beliefs still surround the door, and a cryptic symbol above the doorway fuels many of these theories. But of course, to most visitors to Rome, it's just another mysterious ruin.