The botanical gardens in Floriana were originally two private gardens which were later merged. They were the property of Knight (later Grand Master) Don Emmanuel Pinto de Fonseca and Bailiff Ignatius de Argote et Gusman.

The property belonging to Pinto was eventually purchased by Bailiff de Argote to build his summer residence when Pinto was elected Grand Master in 1730. Fra Carolus Giacinto, appointed the first chair of Natural History at the University of Malta in 1800, tried to establish a botanical collection at Argotti and made several important contributions.

The original summer house of Bailiff de Argote has recently been rehabilitated and converted into an exhibition hall, museum and visitor’s centre.

The nymphaeum, which is quite in a bad state of preservation and is undergoing restoration, bears the coat-of-arms of the Bailiff on the ceiling. This is an ornamental grotto with its interior formerly completely lined with an intricate mosaic pattern formed by rustic rocks, red coral, calcite crystals, sea shells and coloured pebbles. At the back of this grotto, there is a statue of Diana supported by three dolphins. Even the floor was paved with hand painted majolica tiles that depict the nymphaeum.

The Argotti Nymphaeum at Floriana was included in the Antiquities Protection List of 1932 and was scheduled by Mepa as a Grade 1 national monument as per Government Notice number 1082/09 in the Government Gazette dated December 22, 2009.