Abstract: A construction kit for a rail vehicle contains at least one bodyshell for a body of the rail vehicle, at least one door for the rail vehicle and at least one first window for the rail vehicle. The bodyshell has a first door field for fitting the door, which door field is delimited by two adjacent door columns of the bodyshell. The construction kit further contains a frame to be fitted into the first door field, which can be detachably connected to the bodyshell and which has at least one window bar, which, in conjunction with the door columns, delimits a first window field for fitting the first window in the fitted state of the frame in the first door field.