On 10 October 1964 representatives of CERN’s Member States came to see for themselves the progress made during the laboratory’s first decade and to hear about plans for the future. On 30 October Director-General Victor Weisskopf invited all staff for a glass of wine to celebrate, and declared 2 November an official holiday.
You can read the official speeches here, or you can read R. W. Penney’s ‘unscientific recollections’ in the CERN Courier. Penney preferred speak of an eleventh anniversary, since he said CERN really took off in September 1953, when the various groups began to centralise in Geneva. The Meyrin site was still a ploughed field, so they worked where they could; he summed up life in the early days as ‘exhilarating’ and ‘exhausting’.