This Castle is Everywhere
If every movie and TV series happened in the same fictional universe, many buildings would exist in many identical copies around the world.
Hatley Castle, an old mansion now part of Royal Roads University in Victoria near Vancouver, British Columbia, Canada, is one of those often seen buildings. (during World war II it was planned to move the British Royal family into Hatley castle if they had to flee to Canada.)
It has appeared as the Senator's house in The Changeling (1980). The Senator's house could be in Seattle, Washington, near Washington DC, or somewhere else.
It was a place the Russian President left in a helicopter in Canadian Bacon (1995).
It was the headquarters of the San Francisco branch of The Legacy in the series Poltergeist: The Legacy (1996-1999).
In Masterminds (1997) it was the Shady Glen School in California.
It was the mansion of a British duke somewhere n the UK in The Duke (1999).
It was the Luther mansion, transferred from the old country to Smallville, Kansas in Smallville (2001-2011).
It was professor Xavier's school for mutants in Westchester County, New York in X-Men 2 (2003).
It was the Osborne Mansion near New York City in Fierce People (2005).
It was professor Xavier's school for mutants in Westchester County, New York in X-Men: The Last Stand (2006).
It was professor Xavier's school for mutants in Westchester County, New York in X-Men Origins: Wolverine (2009).
It was professor Xavier's school for mutants in Westchester County, New York in X-Men: First Class (2011).
It is the Queen Mansion in Starling City in Arrow (2012-).
It is Auradon Prep School in the fictional Kingdom of Auredon in the Disney TV movie Descendants (2015) and in Descendants 2 (2017).