There really is a Frankenstein Castle. "Burg Frankenstein" is located in the hills just south of Darmstadt, Germany.
The
legend of a monster and mystery of creation. The town of Darmstadt is about
half an hour from Frankfurt, a winding road
takes you up a mountain to the ruins of a castle called Frankenstein. An
original fortress was first built in the 10th Century. The current castle was
constructed beginning in the 13th Century with additions in the next two
hundred years. Abandoned as a residence in the late 1600's, serving for awhile
as a prison and then completely forgotten and a ruin ever since with some
walls, an intact though damaged distinctive tower and a small chapel, said to
be haunted.
The Darmstadt Castle Frankenstein was resurrected in romantic age of the 1800’s as a part of the era’s fascination with gothic and romantic literature and the publishing of Mary Shelley’s famous novel of “Frankenstein” in 1818. The inspiration for Mary Wollstonecraft Shelley’s brilliant, haunting work has been the subject of speculation ever since it’s first printing. Connections of the name of the novel with an actual place have been tantalizing, though never proven. The novel of Frankenstein has very little to do with a castle, which was more an invention of James Whale’s iconic version of the story in the Universal film with Boris Karloff, indelibly etched as the monster and castle as a romantic setting for a film.
Mary Shelley’s inspiration is more complex. In the novel, Victor von Frankenstein is not German at all but Swiss from Geneva. Her story was most famously begun at Lake Geneva in the summer of 1816. The science student's undetailed creation of an unnamed “creature” were carried out at Ingolstadt University and most of the story takes place in Switzerland, the Alps, and on a ship. There is a suggestion that Mary Shelley visited the Darmstadt Castle Frankenstein ruin on a boat trip down the Rhine River in 1814. There is no record of a visit to Darmstadt, or mention of it in her journals. She perhaps may have heard from Byron, who spent more time in Germany than the Shelleys, of the castle and its legend of physician, crackpot theologian and alchemist, Johann Dippel, rumored to have tried to raise the dead by experimenting with human corpses in the castle in its days as a prison. Dippel was trying to discover the alchemist's "Elixer Vitae" potion of eternal life from blood and body fluids.
Since 1972, the castle has hosted annual Halloween parties to pay homage
to the monster of Frankenstein, the student whose god-like ambition was
eternalized in a literary milestone.