Hit the Target's Fortress was Hit the Target's base, along with his ship, underwater base, and hot air balloon. It was used for trapping Stampy's dogs. Stampy then destroyed his house as part of his Village demolition plan and as a revenge after HTT stole his dogs.
After spending much time in the Nether, Hit the Target themed his new base after nether rack, nether brick, and fire. There is also a secret redstoned underground base used for storing stolen dogs.