A construction machine for processing a road surface, in particular a road milling machine, comprising: - a horizontally rotatable milling drum arranged in a milling drum box, - a drive device having a drive arranged outside the milling drum box, the drive shaft of which drive extends in the longitudinal direction of the machine, and a drive transmission, which is configured in such a way that it transmits a drive force from the drive to the milling drum, which transmission is configured in a stepped manner having a gear stage, which comprises a bottom transmission part and an upper transmission part, wherein the offset formed by the gear stage is most great, and which drive transmission is guided from outside through a side wall of the milling drum box to the milling drum, - in the bottom transmission part a driven axle and in the upper transmission part a driving axle running parallel to the driven axle and functionally coupled to the driven axle, wherein the bottom transmission part is arranged essentially in the milling drum box and the upper transmission part is arranged essentially outside the milling drum box, and wherein the upper transmission part is followed by an angular gears for the functional connection to the drive shaft of the drive, characterized in that - a side plate of the construction machine height-adjustable relative to the milling drum box is configured to have an unchangeable area, and - a housing shielding the drive transmission off toward the outside at least in the region of the gear stage and having a housing stage comprising - in the vertical direction - an upper and a bottom region, wherein the housing comprises a side plate bulging in the upper region of the housing stage, into which bulging the side plate can be driven into when being lifted. - a horizontally rotatable milling drum arranged in a milling drum box, - a drive device having a drive arranged outside the milling drum box, the drive shaft of which drive extends in the longitudinal direction of the machine, and a drive transmission, which is configured in such a way that it transmits a drive force from the drive to the milling drum, which transmission is configured in a stepped manner having a gear stage, which comprises a bottom transmission part and an upper transmission part, wherein the offset formed by the gear stage is most great, and which drive transmission is guided from outside through a side wall of the milling drum box to the milling drum, - in the bottom transmission part a driven axle and in the upper transmission part a driving axle running parallel to the driven axle and functionally coupled to the driven axle, wherein the bottom transmission part is arranged essentially in the milling drum box and the upper transmission part is arranged essentially outside the milling drum box, and wherein the upper transmission part is followed by an angular gears for the functional connection to the drive shaft of the drive, characterized in that - a side plate of the construction machine height-adjustable relative to the milling drum box is configured to have an unchangeable area, and - a housing shielding the drive transmission off toward the outside at least in the region of the gear stage and having a housing stage comprising - in the vertical direction - an upper and a bottom region, wherein the housing comprises a side plate bulging in the upper region of the housing stage, into which bulging the side plate can be driven into when being lifted.