Cacti are extraordinary plants - they have adapted to survive in very dry places by storing water inside their thick stems. Even though Monaco's climate is warm and sometimes dry, most of the cacti in the Jardin Exotique originally come from deserts in North and South America, Africa, and Madagascar. The garden brought them all together in one dramatic clifftop spot.
The paths through the garden wind up and down the cliff face, with the sea glittering below. Some of the cacti are covered in sharp spines, while others are round and smooth or look like long green fingers reaching up. Plants called succulents store water in their fat, waxy leaves - if you squeeze one gently, you can feel how firm and full of moisture it is.
Underneath the garden, there is also a cave called the Grotte de l'Observatoire, full of stalactites and stalagmites - these are the pointy stone shapes that grow over thousands of years as water drips through rock. Scientists have found ancient bones of animals and early humans there, showing that people sheltered in Monaco's cliffs a very long time ago.