Idiom, Rome was not built in a day

As you know, Rome was a powerful and vast empire. It was built in a very long period of time. But that's not waht this idiom literally means. It means that it it takes a lot of time to do an important project or job, so patience is required.

Example:
- I'm so tired
- Oh, why is that for?
- I've been making an important project, and I still don't finish
- Well, Rome wasn't built in a day, was it?