The Legends of Castle Frankenstein

What is the true story of Castle Frankenstein, the inspiration for Mary Shelley's famous novel? Was there ever a mad scientist? A monster? A pursuit across the Arctic ice? Because there is a Castle Frankenstein, and you can go there and walk around the ruined stones, poke around in the forest, and eat lunch. The legends that get told by the people who work at Castle Frankenstein are strange, but the layers leading downward into the truth are stranger.
And stranger... An alchemist with no soul. A mysterious object falling from the sky. Terrified peasants with pitchforks and torches. An eerie whistling that echoes through the forest. A fallen tower. The elixir of life. How much is real? How much is just legend?And just how much of it are the locals covering up?