The Kolomo Garrison Ruins is a location from The Legend of Zelda: Breath of the Wild. It is located in the southern part of the Hyrule Field region by Lake Kolomo. A Korok can be found inside the largest building. If Link clears away a pile of leaves and lifts up a rock he finds under them, the Korok will appear and give him a Korok Seed.
The Master Trials
Upon "The Master Trials" DLC pack installation and during the side quest "EX Treasure: Ancient Mask", Link can find a Treasure Chest containing Majora's Mask and buried just outside of the largest building of the Kolomo Garrison Ruins by using the Magnesis Rune.
Many locations in Breath of the Wild are named after characters or locations from previous games. As such, the Kolomo Garrison Ruins may be named after the Lokomos.