As an organisation with more than 60 years of history, CERN has created large volumes of data of many different types. This involves not only scientific data – about 420 petabytes (420 million gigabytes) of data as of the beginning of 2019 from past and present high-energy physics experiments – but also many other types, including photographs, videos, minutes, memoranda, web pages, etc. CERN hence faces the challenge of preserving its digital memory. Data formats and the tools to access them change constantly, and constant effort is required to tackle the issue, but interestingly, many of the tools that are relevant for preserving data from the LHC and other experiments are also suitable for other types of data. CERN is at the forefront of this effort and participates in the DPHEP (Data Preservation in High Energy Physics) collaboration as a founder member.