Age of Origins City Level Requirements: Main Hall Upgrades & Uranium

Part of the Base Building series:

• Building Priority Guide: The upgrade order philosophy behind this chart-reading.
• Beginner's Guide Hub: The full new-commander picture.

Quick Answer

• Every Main Hall level follows the same prerequisite pattern: named buildings at one level below the target — Main Hall 38 wants City Wall 37 and Embassy 37; Main Hall 41 wants Wall 40 and Embassy 40.
• Uranium enters the bill at Main Hall 31 and gates every level after it.
• Uranium comes from the Core Mining Station — which activates at city 30, and only once your nation has at least 30 level-30 cities.
• The cap has climbed over time (38 in early 2025, then 41); assume it keeps moving and plan the pattern, not the number.
• Your real bottlenecks at high level are uranium logistics and the prerequisite chain — not the food and oil bill.

Reading the Requirement Pattern

Players hunt for "upgrade charts," and charts exist — but the chart is less useful than the pattern it encodes, because the pattern is what lets you plan levels you haven't seen yet.

Every Main Hall level asks for three things:

1. Prerequisite buildings at (target − 1). The recurring names at the top end are City Wall and Embassy — 38 wants both at 37, 41 wants both at 40. Which buildings appear varies by level band, but the minus-one structure holds throughout.
2. A resource bill of food, oil, and steel that grows into the hundreds of millions.
3. From level 31 onward: uranium.

The planning consequence is the habit from the building priority guide, now with teeth: read the next level's requirement list before you finish the current one. At high levels, a surprise "Embassy 39 required" is weeks of delay — the Embassy has its own prerequisite chain and its own nine-figure resource bill. Veterans level the known prerequisite buildings in parallel with the current Main Hall push, so the next push starts the day the current one ends.

Per-level numbers shift with patches and new caps, so we won't reprint a table that will be stale by the next mega-update — pull the current level's numbers in-game and verify against a maintained chart site when planning a burn.

Uranium: The Level 31 Wall

Through Main Hall 30, city growth is a resource-and-time problem you can brute-force with gathering discipline and speedups. Level 31 introduces uranium, and uranium is deliberately not brute-forceable.

Here's the supply chain you're signing up for:

• The Core Mining Station is the source. It activates once your city hits 30 — but the building itself only becomes available when your nation has at least 30 cities at level 30. Your endgame progression is, by design, tied to your server's health. On a dying server, this hurts; factor it into any migration decision.
• Activation is expensive: on the order of 108 million food, 108 million oil, 30 million steel, and 17 million minerals. Budget for it before you're staring at a level-31 upgrade screen.
• Mining is a routine, not a purchase. Deep Mining opens four mine sectors with uranium mines of varying levels; sector availability scales with eligible commanders. Your personal uranium storage caps around 300 (350 with the Uranium Card), and you need to collect at least every 10 hours (12 with the card) or production idles against the cap.

That last point is the real lesson: from 31 onward, Main Hall progress is paced by a daily uranium collection habit the way early progress was paced by build queues. Miss collections and no amount of resources buys the time back. Uranium is also a natural alliance coordination topic — where the mines are and who's camping which sector matters.

One myth to bury while we're here: there are no "golden building blocks" in Age of Origins. That item belongs to some other game's guide leaking into search results. Uranium, minerals, and the standard three resources are the whole bill.

The Moving Cap

Main Hall's ceiling was 38 as of early 2025; it has since climbed to 41, and Camel's history says it will climb again. Three planning rules fall out of that:

1. There's no "done." Build your economy — and your research — like the treadmill continues, because it does.
2. Cap raises reset the race. When a new band opens, the commanders positioned with stocked uranium routines, pre-leveled Walls and Embassies, and banked speedups clear it weeks before everyone else — and those weeks are power gaps in every kill event.
3. Verify against a maintained chart when you plan a specific push. Numbers in any static guide (including this one) age; the pattern doesn't.

What City Levels Actually Buy You

It's worth remembering why this grind pays. Main Hall level is effectively your account's tech level: it caps every other building, which cascades into troop tiers through Camps (troop guide), unlocks late systems like warplanes (your warplane count is tied to city level) and Titans, and raises production and defense across the board. Every requirement in this guide is the tollbooth on the only road to the late game.

The High-Level Checklist

1. Read two levels ahead, and level Wall/Embassy-class prerequisites in parallel.
2. Activate the Core Mining Station the moment your city and nation qualify — with the resource bill saved up in advance.
3. Collect uranium on schedule, every day. Set the alarm; the cap is unforgiving.
4. Time the burn: land big Main Hall completions inside construction-scoring event phases (Strongest Commander) — a level this expensive should always score twice.