Which country has Monaco's only land border?

Monaco’s only land border is with France.

The principality is a tiny coastal enclave on the French Riviera, surrounded on its landward sides by France and opening south onto the Mediterranean Sea. Its border touches four French communes: Cap-d’Ail, La Turbie, Beausoleil and Roquebrune-Cap-Martin.

This arrangement reflects Monaco’s historical territorial changes. The principality once included the towns of Menton and Roquebrune, but it ceded them to France in 1861. Monaco’s modern territory is therefore almost entirely enclosed by France, while its maritime boundary extends into the Mediterranean.

A common mix-up is Italy: Monaco lies relatively close to the Italian border, but Italy does not touch the principality. The border is also exceptionally urban, passing through densely built-up areas where streets and neighbourhoods lie immediately on opposite sides of the international boundary.