Frankenstein is Romantic in many ways. In no particular order, they are as follows:
Victor's turn to older sources than modern science for the seeds of his discovery.
The emphasis on passion throughout the book.
The wild settings—the arctic, the mountains, the lakes—and the appreciation shown for them.
The creature teaching itself to read echoes Romantic ideals of childhood. Likewise, the poor family with blind man embody the pure and good peasants praised by Romantic writers.
Finally, some of the books the creature finds are Romantic classics.