Archaeological excavations show that Mound B's first two construction phases took place during Etowah's Late Etowah Period, A.D. 1100 to 1200, creating a small platform mound about one half of its final size. After a short period of abandonment, construction on Mound B resumed from A.D. 1250 to 1325, expanding the mound's footprint to the north and adding structures on its summit. Along Mound B's western periphery, archaeologists found the remains of Structure 3, a series of rebuilt circular buildings about 42 feet in diameter. Its circular ring of posts and changes in soil texture and color suggest that the center lacked posts, served as a hearth, and had no roof. A six-inch-wide trench ran from the central hearth westward out of the entrance and most likely drained liquids used to extinguish the hearth fire, while other evidence points to an open-walled, shed-like structure. A palisade enclosed Structure 3 and the surrounding area. Structure 3 probably served special functions associated with a restricted and probably elite segment of Etowah society, and it appears to have been burned and rebuilt with each new construction effort at Mound B. During the height of Etowah's occupation, about A.D. 1325 to 1375, a terrace was built over Structure 3 and a new rectangular building, Structure 4, was constructed on it, apparently serving Etowah's people in the same manner as Structure 3.