Guide to Taking a Screenshot

Screenshots in Cities:Skylines are handled through Steam. The hotkey is F12 by default although you can change that if desired.

Changing the Screenshot Options

• Go to the Steam Menu and select Settings
• Go to the "In-Game" tab.
• Make sure that "Enable the Steam Overlay while in-game" is checked off.
• The Screenshot shortcut key can be customized, as well as the screenshot folder.
• By default, it will save everything as a jpg. If you'd like a higher quality png, check off the box that says "Save an uncompressed copy".
• Note: If you change the save location, you'll need to restart Steam for the changes to take effect.  

The default location is stored deep within the ProgramFiles(x86) folders. I'm guessing it's not the same for everyone, but it will look something like:

C:\Program Files(x86)\Steam\userdata\*random_numbers*\*more_numbers*\remote\*more_numbers\screenshots

View Screenshots

While in Steam, go to the View menu->Screenshots

There you can see a preview of each of your screenshots or click on the "Show on Disk" button to view it in windows explorer.