When Does "Frankenstein" (1818) Take Place?
"Frankenstein; or, The Modern Prometheus" is a science fiction horror novel written by Mary Shelley that released January 1st, 1818. So when is "Frankenstein" set?
It takes place roughly in the years:
We know this because early in the main action Doctor Victor Frankenstein attends the real-world University of Ingolstadt, which closed by royal decree in May of 1800 AD. So it must be before May of 1800 AD at the beginning of the story.

~1790s AD
We know this because early in the main action Doctor Victor Frankenstein attends the real-world University of Ingolstadt, which closed by royal decree in May of 1800 AD. So it must be before May of 1800 AD at the beginning of the story.
[Scholars have noted that Victor seems to quote the epic poem "The Story of Rimini" (1816), first published in 1816 AD but the phrase "very poetry of nature" is generic enough that it could be a coincidence in the diegesis of "Frankenstein". Either way, the frame narrative that takes place after the main action is expressed through letters dated in the 1700s.]
Furthermore, a letter from Victor's father Alphonse Frankenstein sent during the main action is dated for "May 12th, 17—". So it is certainly during or after 1700 AD.
More specifically, about halfway through the novel, Frankenstein's Creature tells us, " 'The book from which Felix instructed Safie was Volney's Ruins of Empires.' " Constantin-Francois Chasseboeuf, comte de Volney published Les Ruines, ou méditations sur les révolutions des empires (The Ruins, or Meditations on the Revolutions of Empires) in 1791 AD and presumably, this is either the book the Creature is talking about or a fictional book in the diegesis of "Frankenstein" based on it. So it is probably after 1791 AD.
Additionally, "Frankenstein" is a rare example of a double frame-narrative: explorer Robert Walton .
-So in frame 1, all the letters in the prologue and the epilogue (starting halfway through chapter 7) written by written by Walton include dates that end in "17—" and the first one includes the phrase: ..."as I walk in the streets of Petersburgh". The real-world city of Saint Petersburg was founded on May 27th, 1703 AD. Its spelling was not codified for many years and the "Saint" was dropped fairly often BUT on August 31st, 1914 AD it's name was officially changed to Petrograd (and then to Leningrad on January 26th, 1924 AD). It did not return to the original name until September 6th, 1991 AD. So it must be after May of 1703 AD and it is extremely likely it is before August of 1914 AD.
More specifically, in his second letter Walton writes, "I am going to unexplored regions, to 'the land of mist and snow'; but I shall kill no albatross, therefore do not be alarmed for my safety." The sentence makes no sense unless Robert Walton has read the poem "The Rime of the Ancient Mariner" (1798) as it refers to a specific plot point from it. It is after the first publication of the poem in the collection Lyrical Ballads on October 4th, 1798 AD but his letters are still dated "17—" nearly to the end 1 year later, so it must be late 1798 AD at the start of the frame narrative.
1,799 - 1 = 1,798.
Specifically, the first letter is dated "St. Petersburgh, Dec. 11th, 17—" and includes the sentence "I do not intend to sail until the month of June". The last is dated "September 12th." So at least one calendar year has passed between the beginning of this frame and its conclusion, making it December of 1798 AD at the start and September of 1799 AD. at the end of this frame.
-So in frame 2, .
It was adapted to the stage in 1823 as "Presumption, or the Fate of Frankenstein", to film in 1910, to film again in 1931, as a comic-book in 1945, another film in 1957 titled "The Curse of Frankenstein", a film in 1977 called "Terror of Frankenstein", another comic-book (graphic novel?) in 2019, and, yet again, to film in 2025.