Cities: Skylines - How to Upgrade Buildings

gamerant.com:

A central feature of Cities: Skylines is the set of «growable» buildings that go up by themselves in designated construction zones. These buildings are the main source of income within the game, and so players must keep the citizens who build these structures happy.

Something else growable buildings can do is upgrade to new levels. Residential buildings have five levels each, and commercial, industrial, and office buildings have three levels. Players will want these levels to be as high as possible, because max-level workplaces can house more workers, max-level residences can hold more families, and both types of building pay more in taxes. Here's how to get those levels up.

Most Stressful Management Games

The variable with the single biggest impact on building level is education. Educated citizens will upgrade their homes and workplaces, and the better their education is the more upgrades these buildings will go through.

To educate their citizens, players will need to build up an infrastructure of elementary schools, high schools and universities. These buildings unlock at the Little Hamlet, Tiny Town, and Big Town milestones respectively. One wrinkle is that only children can go to elementary school, only teens can go to high school, and only adults can go to a university. In addition, citizens can only upgrade their education level by getting the lower level first.

Since incoming citizens who populate a new housing development are always uneducated, this means residences will always slowly improve over time, assuming the city has enough capacity for every potential student. On the other hand, industrial and office zones draw on the city's existing population, and so if the citizens are highly educated and other