The Hidden Stronghold is a secret fortress hidden within the mountains of Asgard, that was built for its use during the Trolls invasion of Asgard.
Upon Hela's return, Heimdall gathered dozens of Asgardian citizens in the stronghold within the mountains of Asgard. Searching for the sword Hofund so as to conquer all the Nine Realms, Hela and Skurge located the Stronghold as its location had been disclosed by an Asgardian. Hela created massive spikes to tear down the door of the fortress but found it to be entirely empty as Heimdall and all the Asgardians had fled to the Bifrost Bridge.
- The doors of the Hidden Stronghold feature a large image of the mythical tree Yggdrasil.