Lessons from CTF3

The CLIC Test Facility (CTF3) was built to demonstrate the feasibility of the CLIC two beam acceleration scheme. The main issues to be verified were the high current drive beam generation using a fully loaded highly efficient linac and a beam combination scheme, based on transverseRF deflectors, to increase beam current and bunch repetition frequency. The drive beam has been used for GW level RF power production and two beam acceleration experiments. CTF3 was also a test ground for development of many accelerator technologies.Its operation was concluded in 2016 and in this contribution the results relevant for the CLIC design as well as for the whole accelerator physics community will be presented.