This little square, located only a short walk from The Royal Palace, is dedicated to Queen Isabel II, daughter of Fernando VII, and it also contains a statue commemorating her.
One of the most prominent buildings in the square is Royal Theatre, major opera house in the city.
The plaza is also lined with various places where you can have a bite.
Wikipedia https://en.wikipedia.org/wiki/Plaza_de_Isabel_II_(disambiguation)
Address 4 Plaza de Isabel II, Madrid 28013, Spain
Coordinates 40°25'5.289" N -3°42'34.182" E