However, if you like to map camera controls to mouse movements, it’s possible that you unintentionally overwrote the default rotation control implementation. Right-clicking is the default control implementation for object rotation.
This gives you a great deal of flexibility when it comes to structure orientation. Alternatively, you can right-click and hold on that object, and rotate it freely by a degree at a time. To change the orientation of any object, simply right click on it. The method for rotating objects in Cities: Skylines is relatively intuitive if maybe not perfectly explained. We did the research, and we have the answers you need. In a game as open-ended and flexible as this one, the ability to position your structures exactly how you see fit can make a huge difference toward the aesthetics of your cities.
How to rotate objects in Cities: Skylines.