There are 2 large fountains in Rossio Square (also known as Pedro IV Square) in Lisbon, each with 4 mermaid statues. map
The bronze sculptures were created by sculptors Mathurin Moreau and Michel Lienard, and were installed with the fountains in 1889. They were created in Val d’Osne, France and then imported to Portugal.
The centerpiece of these fountains appears to be amongst several casts from an original 1855 fountain by Michel Joseph Napoléon Liénard, featured featured at the 1855 Paris World Fair.
Other copies with minor variations can be found across the world, including the Steble Fountain in Liverpool, the Tourny Fountain in Québec, Fuente Francesa Avenida 9 de Julio on Av. Cordoba y Cerrito in Buenos Aires and the Fountain of Ceres in Salvador de Bahia, Brazil. The fountain is decorated with the figures of Neptune, Amphitrite (Neptune’s wife), and Acis and Galatea, a couple from Greek mythology.
Amphitrite was arguably a mermaid, and in Greek mythology is the mother of Triton.