Herald Square

 is a real-life neighborhood of New York City's borough of Manhattan, located in the southeast corner of the Garment District just south of Midtown Manhattan. Its geography has been fictionally represented in some Teenage Mutant Ninja Turtles stories.

2012 TV series
In the season 1 episode I, Monster,, now calling himself the Rat King, set up a lair in an abandoned utility junction beneath Herald Square. He psychically linked with, trying to control him along with the other rats of the city. Splinter, also a psychic in his own right, had also been observing Falco through the link, and managed to warn his sons of Falco's activities and the location of his lair beneath Herald Square.

IDW continuity
Though not mentioned directly by name, the Zones of Criminal Control maps in the  story arc show 's directly controlling the criminal underworld activities in a broad swath of western Manhattan, mostly centered in Hell's Kitchen and headquartered in Chelsea, but also encompassing other smaller nearby neighborhoods including Herald Square.