The Rally Spot governs your own march size / rally capacity (troops per march). Builds Lv1-50, each level requiring the matching Keep level; from Lv26 additionally the matching Army Camp level (Army Camp 26 at Lv26 ... 50 at Lv50), so Army Camp gates Rally Spot from Lv26 up. No troop-tier Unlock column. Key milestone: Duty Officer at Lv35 (increases March Size Capacity; ideal Toyotomi Hideyoshi, Niwa Nagahide, Zhang Liang). March size is raised through multiple systems beyond this building (12 ways to increase March Size, max march size by Keep level, and March Size Increase items). Costs: Lv1 780 food/780 lumber; Ore at Lv12; Lv25 ~8.5M/11M/11M/11M; Lv50 ~36.6B/45.7B/45.6B/45.7B. Power 8 to 35,000,000. Speed +0% to Lv17, +30% at Lv18 to +610%. For a bot, Rally Spot level is a primary lever for solo march/gather size (bigger marches = more resources per gather haul); prioritize Lv35 for the March-Size duty officer, and keep Army Camp leveled to unblock Rally Spot Lv26+.
Original research source: Evony Guide Wiki