The Extremely Large Telescope, adorning the cover of this issue, is due to record first light in 2025 and will outperform existing telescopes by orders of magnitude. It is one of several large instruments to look forward to in the decade ahead, which will also see the start of high-luminosity LHC operations. As the 2020s gets under way, the Courier will be reviewing the LHC’s 10-year physics programme so far, as well as charting progress in other domains. In the meantime, enjoy news of KATRIN’s first limit on the neutrino mass, a summary of the recently published European strategy briefing book, the genesis of a hadron-therapy centre in Southeast Europe, and dispatches from the most interesting recent conferences. CLIC’s status and future, the abstract world of gauge–gravity duality, France’s particle-physics origins and CERN’s open days are other highlights from this last issue of the decade.
