Digitalisation has reached the shores of central banking. Central Bank Digital Currencies (CBDCs) are the public response to privately issued virtual currencies, of which Bitcoin was the pioneer. In this uncharted territory, central banks face a multitude of design choices – “account-based” or “token-based”, offered to the general public or only to a selected group of users – which raise unprecedented legal questions. Entering the digital arena bears great potential for monetary policy as well as risks for the financial system. Finding a balance for each jurisdiction and monetary system will be a key task for central banks in the 21st century.