Stockholm Syndrome is the name given to the psychological phenomenon of captives emotionally bonding with their captors. It's named after a particular bank robbery in Stockholm, Sweden in 1973. During and after their captivity, the hostages criticized police and supported the robbers.
Stockholm Syndrome is not the only psychological condition named after a city. At Atlas Obscura, Frank Jacobs lists other conditions named after Detroit, Boston, Lima, London, Brooklyn, Paris, Florence, Venice, Amsterdam, and Jerusalem.
Paris, Florence, and Venice have peculiar conditions experienced by tourists. Lima Syndrome, which refers to the 1996 hostage crisis at the Japanese ambassadorial residence, is the opposite of Stockholm Syndrome in that the captors become too sympathetic with their captives.
The most interesting on the list is, perhaps, Brooklyn Syndrome. It refers to being argumentative and obstinate with other people, a trait identified with people from Brooklyn, New York.
Photo of the Lima hostage crisis by César Astudillo.