Rossio is definitely one of the most beautiful squares in Lisbon. On any given day you'll see locals on their way to or from work or running errands, markets, street vendors and performers, and of course tourists from all over the world delighting themselves taking in the sights. It's a place where you can find the famous D. Maria II National Theatre, the statue of Dom Pedro IV (Pedro I, imperor in Brazil), a stunning fountain and many cafés surrounding the area, such as Café Nicola founded in 1929. This is still today a traditional meeting point for locals and visitors.
And after having a delicious Portuguese coffee at Café Nicola do not forget to visit the majestic Rossio Train Station.