Pasture is where Spiritual Beasts, Dragons, and Seals are leveled/refined. Construction possible at Keep Lv21; requires Warehouse raised first. Council of State level-ups require both Pasture and Victory Column raised first. All menus usable during Pasture's own upgrade. Spiritual Beast unlock milestones: Lv6 Thunder Scorpion, Lv11 Bird of Hurricane, Lv16 Lord of Lava, Lv22 Behemoth King. Dragon unlock milestones: Lv26 unlocks Dragon feature plus Celtic Demon (needs 300,000 gems) and Jawzahr (needs Jawzahr Dragon Pattern); Lv30 unlocks Fafnir (needs 1,400 Dragon Crystals); Lv35 unlocks each dragon's 3rd Talent (requires that dragon at Lv10). Council of State gating: Pasture Lv27→CoS Lv2 start requirement, Lv28→CoS Lv3, Lv29→CoS Lv4, Lv30→CoS Lv5, Lv31→CoS Lv6, Lv32→CoS Lv7-9, Lv33→CoS Lv10-12, Lv34→CoS Lv13-15, Lv35→CoS Lv16-45 (i.e. Pasture Lv35 is needed for all remaining Council of State levels).
Original research source: Evony Guide Wiki