Elzer Berg, Mountain summit in Limburg-Weilburg, Germany

Elzer Berg is a 291.3 m hill on the western edge of Elz in the Hessian Limburg-Weilburg district, with slopes in Rhineland-Palatinate's Westerwaldkreis. The A3 crosses it between the Diez and Limburg-Nord junctions, and the Cologne–Rhine/Main high-speed rail tunnel runs beneath it. Parts of the Elzer Wald and two FFH protected areas cover its slopes.

The A3 crosses the hill between the Diez and Limburg-Nord junctions, with an 8 km descent toward Limburg at gradients up to 5%. In the early 1970s this slope averaged 350 accidents a year, earning the nickname "Katzenbuckel". In April 1972 four oversized sign gantries were erected on the initiative of the Idstein motorway police and two Limburg hospital chaplains; stationary radar followed in November 1973, the first permanently installed speed cameras in Germany.

The hill gave its name to the Elzer Berg speed cameras, the first permanently installed speed-monitoring systems in Germany, set up in November 1973 after sign gantries appeared in April 1972. The band Die Toten Hosen printed a photo of their Opel Blitz in the album booklet with the note "Spitze 146, radargemessen am Elzer-Berg".

The A3 crosses the hill between the Diez (km 99.0) and Limburg-Nord (km 107.5) junctions, descending about 8 km toward Limburg at up to 5%. Stationary speed cameras sit in the sign gantries only on the Limburg-bound slope; the Montabaur direction has temporary limits shown on electronic boards. The Cologne–Rhine/Main rail tunnel runs beneath the hill.

The hill's name is tied to a road-safety story: in the early 1970s the A3 descent recorded about 350 accidents a year, and in November 1973 stationary radar units were installed here, the first permanently installed speed cameras in Germany. The band Die Toten Hosen printed a photo of their Opel Blitz in the album booklet with the note "Spitze 146, radargemessen am Elzer-Berg".