The Route nationale 4 is a trunk road (nationale) in France between Paris and the frontier with Germany.
The RN 4 has been re-classified around Nancy as the RD 400 as through traffic is now directed onto the Autoroutes A 31 and A 33.
Paris-St Dizier-Nancy-Strasbourg-Germany
The road begins in Central Paris at the Porte Doree and a junction with the RN 6 a separate branch starts in the Bois Vincennes with a junction with the RN 34 before heading south through the park and meeting the other branch the Avenue de Gravelle. The road follows the southern edge of the park. It crosses the A4 autoroute and continues east as the Avenue des Canadiens and then crossing the River Marne. It passes through the suburbs of Joinville-le-Pont and Champigny-sur-Marne. It then passes through Chennevières-sur-Marne and an industrial area before reaching open countryside and the Northern edge of the Forêt de Notre-Dame.
The road has a junction with the RN 104 and becomes a dual-carriageway and now bypasses Ozoir-la-Ferrière and then Gretz Armainvilliers south of the Forêt d'Armainvilliers. The road passes through rolling countryside past the Château de Boulayes. This is cheese county with the road taking an eastern course after Rozay-en-Brie. The road crosses the Forêt de la Traconne to Sézanne.
The road passes over open flat countryside increasingly sparsely populated reaching RN 77 and A 26. The road then drops from 200 m to 98 m at Vitry-le-François and the River Marne again. There is a junction with the RD 44.