BLR structures in NGC 7469, NGC 3783, NGC 5548 (two epochs), and 3C 390.3 scaled with respect to their individual Schwarzschild black hole radii (based on corrected turbulent velocities v_turb). The emitting regions of the highly ionized lines of the individual galaxies are connected by a solid line. The Hβ emitting regions are drawn in red. Those of NGC 5548 are connected by a solid red line. The dot at radius zero gives the size of a black hole with 20 Schwarzschild radii.