Frontiers of the Roman Empire

Frontiers of the Roman Empire is a World Heritage Site. The site includes three walls in different parts of Europe. They were part of the frontiers of the Roman Empire.
Limes.
Limes (plural: 'Limites') is the Latin name of walls at the border of the Roman empire. There were many such fortifications.
The Latin word has a number of meanings, but the most common one is border.
The term "limes" was used by Roman writers to describe paths, walls, boundary stones, rivers marking a boundary, but its meaning was not the same as the modern boundary.
Some notable examples of Roman "limites" are: