This plaza was nicknamed Cinelândia because it had several historic theaters spring up around it. The most famous is Theatro Municipal. It was built in 1905 and holds the city ballet, opera, and orchestra.
The theatre is luxurious both inside and out. It’s considered to be among the most stunning theatres in Brazil.
Other prominent buildings on the plaza include the Palácio Pedro Ernesto (Rio de Janeiro city hall) and Biblioteca Nacional, the largest library in Latin America and the 7th largest in the world. It was established in 1810. There’s also the Centro Cultural de Justiça Federal (courthouse) and the Museu Nacional de Belas Artes (Fine Arts Museum).
Besides the historic buildings, the plaza is also a great place for people watching. There was a book fair taking place when I visited.
Note: The only time you should visit this area is during the weekdays. Nights and weekends are absolutely off limits. Nobody lives in this area and it is not safe to be there alone. You should also be aware of your surroundings and be very careful with valuables.