In-plane distribution of the sample of 50 far disk bona fide CCs with homogeneously determined distances based on VVV near-IR photometry. Our sample of spectroscopically confirmed CCs is shown here using blue circles. The blue open squares represent the complementary sample of OGLE-VVV CCs. Distance error bars are indicated for each star and the point sizes are inversely proportional to the Cepheid ages. The far side disk maser source presented in Sanna et al. (2017) (blue star inside circle) is shown with its corresponding error bar. The Sun is located at (X = 0 kpc, Y = 0 kpc) and the Galactic center is marked with a red cross at (X = 8.15 kpc, Y = 0 kpc). The colored sections are the log-periodic spiral arm segment fits based on VLBI trigonometric parallaxes of HMSFRs by R19. The dash-dotted circles in the background mark Galactocentric radii ranging from 4 to 24 kpc.