More than a million people, mainly Jews, died at the largest concentration camp established by the Nazis during the Second World War.
Some solemn places across the country are asking players of "Pokemon Go" to go away.
Pokemon Go - having become a global phenomenon in just days - is set to make big money but is also creating controversy.
If it wasn't bad enough that people were playing Pokemon Go at Holocaust museums, the gaming craze has now required a prohibition by the most infamous death camp of Nazi Germany.
Other locations, like National Mall and Memorial Parks have embraced the hot game.
Folley said the informative site's appearance on the "Pokemon Go" list of places to see and visit could reach some people who aren't aware of its existence. The Pokemon are randomly distributed throughout the game, but it doesn't seem like it would be too tough to prevent them from appearing in certain spaces. The Washington Post reported that the museum contains three different "PokéStops" - real-life sites where players can redeem in-game items. "We are looking into how the Museum can be removed from it", he said.
Niantic did not immediately respond to inquiries about the alleged Koffing sighting or if there was any way to honor the Holocaust Museum's request to stop Pokemon from popping up inside its building. "It's disrespectful on many levels".
Hollinger stressed that the museum is generally pro-technology and encourages visitors to use social media to share how their experiences with the exhibits moved them.
The users of "Pokemon Go" will stay at the PokeStops to catch Pokemon easier and go to the gym to train their catch by letting them fight with other monsters of different players. "But this game falls very much outside that", he said. "We ask all visitors to refrain from such activity", the Arlington Cemetery said on Twitter.
The harbingers of published grammar in the US, AP Stylebook, announced today the rules for writing about Pokemon Go.