The U.N. Plaza Hotel is the hotel in New York City where Susannah Dean and Mia went to palaver and wait for Richard Sayre's call. The room was paid for using money given to them by the sköldpadda-influenced Mathiessen Van Wyck.
Susannah left Black Thirteen in the hotel room for Jake Chambers and Donald Callahan to find. Jake and the Pere almost killed themselves while under the sway of Black Thirteen. Fortunately, they were able to shake off its influence enough to close its box.