The Hyrule Castle Town Ruins are a location from The Legend of Zelda: Breath of the Wild. They are located in the Hyrule Field region of Central Hyrule, south of Hyrule Castle and north of the Sacred Ground Ruins. The Katah Chuki Shrine can be found within the West Castle Town's Quarry Ruins south of the Water Reservoir.
Little of the town still remains as most of was destroyed and burned to the ground during the Great Calamity. The ruins are littered with damaged Guardian Stalkers and Decayed Guardians. Link can find many Treasure Chests hidden in the walls under spires.
Many of the houses and castle walls protecting the town are destroyed and covered in Malice. The ground is blackened and covered in ash and poisonous Malice. Some of the Malice pools have Glowing Eyeballs which Link can destroy to remove the Malice their connected to. So much of the buildings are destroyed, nothing is obstructing Link's view of the entire town, putting in perspective the true demise of Hyrule Castle Town. However at least two Cooking Pots survived the destruction one in the ruins on the western side of the Central Square while the other is located in East Castle Town. The town's Central Square is connected to Hyrule Castle by a bridge that leads to a large metal doors that Link can move with the Magnesis Rune though must be weary of a Guardian Skywatcher as its patrol route goes over bridge. Though most of it former inhabitants have long since fled or perished during the Great Calamity, several Koroks can be found within the town. One is hidden at the Hyrule Cathedral, another at the Castle Town Watchtower, and two appear on the archway of the metal doors right on the boarder between the town and Hyrule Castle.
A Knight's Broadsword and Knight's Shield can be found on the Central Square fountain's south side and occasionally respawn if Link leaves the area. The fountain has four tablets in each of the cardinal directions, all of which read, “On this day the king opened this spring up to the public,” without ever giving an actual date. The the area is swarming with Guardians after Link awakens, Parcy implies that this is recent development as she used to enter the area while on her way to Hyrule Castle to search for treasure and valuable objects. However eventually the Guardians started appearing and approaching the town to reach the castle became too dangerous even for her. This implies they only became more active as Zelda's seal on Calamity Ganon weakened and Ganon sensed Link had awoken. Two Ancient Pillars where buried on the east and west sides of town which have since risen out of the ground in response to Calamity Ganon's growing power and Link's activation of the Great Plateau Tower. A broken Guardian Stalker can be found on the town's east pillar though Link can only reach it by Paragliding to it from the top of Hyrule Castle's Sanctum. Searching this Guardian will allow Link to acquire a random Guardian Part.