|The Gateway Arch|
|Building Type||Unique Building|
|Build Cost (₡)||80,000|
|Upkeep cost (₡/week)||400|
|Milestone Required||Busy Town|
The Gateway Arch is a level 4 unique building in Cities: Skylines. This is different from the City Arch, which is a level 1 unique building that’s much cheaper and easier to unlock.
To unlock the Gateway Arch, you must have 20,000 squares of commercial zone, and you’ll need to reach the Busy Town milestone (1,200 to 5,000 population, depending on the map).
Until then, you can hover over the Gateway Arch’s silhouette there to check your progress towards the unlock.
Note: As of the 1.15 game version, you may encounter a bug in which ‘Business Park’ may appear instead of the name Gateway Arch.
Take note that the 20,000 squares of commercial zoning will need to be built upon (they cannot be empty zones).
The Gateway Arch is a requirement for the Eden Project monument.
Creating Commercial Zones & Getting Buildings To Grow
Commercial zoning is as simple as painting the squares along roads using the commercial (blue) zoning tool.
Both low-density and high-density commercial will count towards your progress.
However, getting buildings to grow on them is another matter (and is the main challenge of this unlock).
Buildings will only grow in your zones if there is appropriate demand for them.
The demand for commercial buildings is proportional to the size of your population.
According to the Skylines Wiki, your city needs to have 1 commercial worker per 8 citizens for demand to be fulfilled (i.e., an empty demand bar).
This basically means in order to generate enough commercial demand to fill 20,000 squares, you’ll have to keep growing your population.
Tip #1: Provide Access to Education
Even in the early game, your commercial buildings will require at least some educated workers, so don’t forget to provide the schools to supply them.
Commercial zones that experience a shortage of adequately educated workers for too long will get abandoned.
Tip #2: You’ll Need Industry As Well
Expect to have to expand your industry (and office) zoning as well in the course of this unlock.
Industry will serve two purposes:
- Making jobs available in your city, which is necessary in order for your population to grow
- Supplying goods to your commercial zones
If you’re averse to zoning more industry (say, because of the pollution), your commercial zones may need to rely on imports for their goods. In this case, make sure your commercial zones have convenient access to external connections such as the highway or a cargo train station.
Tip #3: The Infinite Demand Mod
If you don’t mind using mods, you can make this unlock much easier by using the Infinite Demand mod.
Note: Using mods disables Steam achievements.
As the name implies, this mod makes it so there’s always a full demand bar for your zones. In other words, any zones you paint will grow buildings.
In fact, with this mod you can simply create a “throwaway” city to unlock the Gateway Arch.
To do that, start a new game and grow 20,000 squares of commercial zoning for the unlock, then close the game. This works because unique buildings stay unlocked across save files (so you’ll be able to build the Gateway Arch in your normal cities).