The Paris Metro is the densest system in the world. Its 15 lines and almost 300 stations connect frequently with RER and SNCF stations.

The Four suburban express lines (A, B, C, D) link Paris with the Ile-de-France region. Line C2 runs to Orly, B3 to Roissy-Charles-de-Gaulle.

Paris also has an extensive bus network with buses run on the 60 or so routes crisscrossing Paris.