An engine pylon of an aircraft having a rear portion, two rear cowls around the rear portion, each rear cowl having an upper fixed cowl and a lower movable cowl mounted articulated on the rear portion, wherein in the closed position the two lower movable cowls are moved close to one another, such that their lower edges are contiguous, wherein in the open position the two lower movable cowls are tilted such that their lower edges are moved away from one another, for each lower movable cowl, a hinge system fixed between the lower movable cowl and the rear portion, and at least one locking system which locks the two lower movable cowls to one another in the closed position. The presence of the lower movable cowls ensures, among other things, easy access to the interior of the engine pylon.