Spread over an area of approximately 15,000 m2, the Exotic Garden is home to a thousand cacti and other succulent plants with stems or hypertrophic leaves which store water. Originally from the planet’s main semi-arid regions, these plants still produce plenty of flowers. The principal flowering seasons are winter (January–February) for South African succulents such as Aloe and Crassula, and spring and summer for cacti, a family native to the American continent.
The enormous trees which line the paths of the Exotic Garden illustrate the age of the collection which served as the basis for the creation of the garden at the instigation of Prince Albert I. Opened to the public in February 1933, and supplemented in the 1960s by a botanical centre and specialist tree nursery, the garden is one of the Principalities most visited tourist attractions.
At the base of the cliff on which the Exotic Garden is situated (called “the observatory” due to the long-standing presence of a small astronomical observatory), at an altitude of 100 metres, there is a subterranean chamber equipped to receive visitors. The limestone rock, carved out by water containing carbon dioxide, is studded with caverns adorned with geological formations bearing evocative names: stalactites, stalagmites, draperies, columns, soda straws...
Expert guided tours of the cave are included in the entry ticket for the Exotic Garden. The tour travels from a depth of 98 metres to a depth of 40 metres (around 300 steps). The chamber plunges down almost to sea level and is regularly explored by local cavers.
The presence of prehistoric humans in the region of the cave is confirmed by the bones of the animals that they ate. These remains also illustrate the climate variations that have taken place over the last 250,000 years. http://www.visitmonaco.com/en/Places-to-visit/Gardens/The-Exotic-Gardens-and-the-Observation-Cave