The most important historical structures which date back to the eighteenth century are the Nymphaeum and the Summer Villa. The Nymphaeum was once completely lined with a decorative motif using black obsidian and white marble pebbles, red coral and calcite crystals. The coat of arms of bailiff Ignatius de Argote y Guzman from which the garden name is derived, is on the ceiling.
The old summer house of Bailiff de Argote has been recently renovated and converted into an exhibition hall, museum of garden history and plant science. The most recently built structure is a modern purpose-built herbarium housing the old dried plant collections together with a small laboratory.
The garden houses different plant collections. Collections include family beds where part of the garden is divided into plots that represent the different plant families. A section is dedicated to Mediterranean Flora where indigenous and endemic plants are present. The national tree – the Sandrac Gum tree, and the national plant – the Maltese Rock Centaury as well as the Olive, Aleppo Pine and Maltese Cliff Orache are also present.
A number of plant collections are housed in the three greenhouses and these predominantly include a collection of cacti and succulent plants. It is good to note that hardy cacti and succulents especially Agaves, Aloes, Gasterias and several members of the Aizoaceae are grown in the open as well; indeed a large outdoor collection forms part of the herbarium roof garden.
Other garden features include the Water Lily Pond located between the greenhouses which hosts aquatic plants including species of Nymphaea and Nelumbo nucifera.