You may be surprised upon arriving to see that inside the mixtlinear basin is housed a bathing tub decorated with handles and a lion face.
Originally, they were intended to be used as decorative pieces for the squares, since water could not reach this area yet. Only in 1626, the project to convert the two tubs into fountains was completed under the direction of architect Girolamo Rainaldi.
Inside the tubs are placed amphora-like sculptures supporting a top basin and a floral ending, resembling the coat of arms of the Farnese family from where the water is spouted.
On one side of the square stands the Farnese Palace, famous for his cornice realised by Michelangelo and nowadays hosting the Embassy of France.