The timeline of Cardiff history shows the significant events in the history of Cardiff which transformed it from a small Roman fort into the modern capital city of Wales.

The word Caerdyf has its origins in post-Roman Brythonic words meaning "the fort of the Taff". The fort probably refers to that established by the Romans. Caer is Welsh for fort and -dyf is in effect a form of Taf (Taff), the river which flows by Cardiff Castle.

50s AD: A settlement was established by the Romans.

75: A Roman fort at Cardiff, where Cardiff Castle now is, was established.

380s: The Romans abandoned Cardiff.

850: The Vikings attacked the Welsh coast. They used Cardiff as a base and then as a port. Street names such as Dumballs Road and Womanby Street come from the Vikings.

1081: William the Conqueror led an army through southern Wales and may have erected defences at Cardiff on the site of the old Roman fort.

1100: A small town outside the castle was establishing itself. It was made up primarily of settlers Norman/Saxon people.