Galactic warp traced by classical Cepheids. The Milky Way disk is divided into 18 slices. The vertical distribution of Cepheids within each slice is displayed in adjacent panels, showing the distance from the Galactic plane z as a function of the Galactocentric distance r. The black dots represent individual Cepheids while the blue line is the warp model, computed with the parameters listed in Table 3 and for the median Galactocentric azimuth of a given slice.