The period and metallicity distributions, and period-Wesenheit relation for MW Cepheids. Top: period distribution of 80 candidate Cepheids in the sample studied in this work. The filled and lined histograms correspond respectively to FU and FO Cepheids. Middle: histogram of metallicities for 65 Cepheids, of which 59 have homogeneous high-resolution spectroscopic metallicities from the C-MetaLL survey (Ripepi et al. 2021; Trentin et al. 2023). Bottom: period-Wesenheit relation in Gaia filters for the sample of 80 stars. The circles and squares represent fundamental and first-overtone mode Cepheids, respectively. Two extreme outliers are marked with their Gaia DR3 source ID.