You cannot enter Spain directly from Monaco.
You can drive, fly, go by boat or train from almost any big city in Europe.
Monaco
Kara Monaco goes by Karebear.
Go to a drive through
The Amazon runs through two countries. It runs through Brazil and Peru.
There are many places to go and things to do in Monaco, see the related link.
The history of Monaco is long and complex. Far too involved to go into here.
1,089.15 kilometres (676.77 miles)The citizens of both Monaco and Nice would be quite surprised to hear that ! - When I lived there I could drive it in less than 15 minutes !
Princess Caroline of Monaco goes by La Bouche D'or.
You would have to go through Spain and possibly Andorra.
Amazonia