Monte Mario is big hill in the city of Rome, Italy. It is really tall and has a big park on top of it where people can go for walks and have picnics.
At the bottom of the hill, there is a big stadium called the Stadio Olimpico where they play really important sports games like football (which is what people in Europe call soccer).
On the very top of Monte Mario, there is a really cool observatory where scientists can look at the stars and learn more about space. They have special telescopes and tools to help them see really far away things.
Overall, Monte Mario is a really cool and important place in Rome where people can enjoy nature, play sports, and learn about space!