The talk will review the largest Russian telescopes – the optical 6-m telescope and the Ratan 600 radio telescope with a ring-type 600 m aperture. Observational methods available to operate at these telescopes, as well as new instrumental studies for these methods – new CCD cameras, spectrographs for the 6-, 1-m telescopes and new radiometric systems for RATAN 600 will be discussed. The most important newest observational results obtained with these telescopes will also be touched in the talk.