“London Greenwich” by Albertistvan, CC BY-SA 4.0 <https://creativecommons.org/licenses/by-sa/4.0>, via Wikimedia Commons

Greenwich is an administrative division in England. Much of Greenwich is reserved for wide, open public areas and fields, but there are several places of interest in the area such as the Royal Greenwich Observatory or the Old Royal Naval College. The observatory is a place that is known for its age, and is regarded with respect in that right. In Frankenstein, Greenwich is mentioned in passing, as a place that Victor visits with Henry early on in book 3 during the two-year span in which Victor has allotted to construct the creature’s other. It’s only mentioned as a place he knows, but considering the areas connections with England’s military, it might be a place signifying power, which is a throughline in the novel. It's also worth mentioning to note that the meniton this place may contribute to the tone of the novel, as at this point, it's known, or at least speculated, that the creature is following Victor and watching his every move from afar. Mentioning a place which houses one of the most old and respected observatories in the country may be a subtle nod to that.

Greenwich | England, Map, History, & Facts | Encyclopedia Britannica