I Have An Impenetrable Fortress

Zhang Dongyun had transmigrated with an Invincible City system.
As the City Lord, he was invincible as long as he was within the boundaries of Invincible City, regardless of his current cultivation level.
Nothing could harm Zhang Dongyun, and he could control the life and death of all living beings within the city.
Moreover, the city would continue to upgrade and expand.