The Red Castle is a gigantic palace-like fortress in the Underland's Outlands home to the evil Red Queen and a location in the 2016 Disney fantasy movie sequel Alice Through the Looking Glass which is loosely based on Through the Looking-Glass by author Lewis Carroll.
The castle is shaped like a giant heart and it clad in crimson red color. It has a number of stairways, hallways and chambers.
It was built by vegetable/fruit-hybrid people under orders from Iracebeth (the Red Queen), though it is unknown the construction of the castle was before or after her rise to power.
It is unknown if the Red Castle is still inhabited or not, after Alice Kingsleigh returned the Chronosphere to the Great Clock at Time's Castle and Iracebeth redeems herself by forgiving her sister for what happened between both of them in the past.