A large boulder is blocking traffic on the Grande Corniche (RD 2564), in both directions, at Vista Palace in Roquebrune-Cap-Martin, Monaco-Matin reports.
A detour along the RD 6007 and 51, via Roquebrune and Beausoleil, has been put in place indefinitely, until work can be completed to secure the cliff.
The incident happened early Saturday morning along the Promenade de la 1re Division française libre, a small winding artery that leads to the Grande Corniche.
According to the mayor of Roquebrune, Patrick Cesari, the double road closure is a preventive safety measure.