We discover the camp from which Vikings invaded Britain, and find groundbreaking new evidence that the world-famous Avebury stone circle isn't just a sacred site but a place where our ancestors lived and worked - a discovery that's also changing our understanding of neighbouring Stonehenge. In Staffordshire, the oldest Iron Age gold in Britain is unearthed - a set of beautiful gold torcs, mysteriously abandoned 2,500 years ago.

We unearth the biggest collection of Roman writing tablets in Britain, giving insight into what Roman London was really like. Off the coast of Kent, we dive into the English Channel to complete the biggest marine excavation since the Mary Rose - an 18th-century East India Company ship, packed with silver. Also in Kent, we're on the detective trail to find the very first evidence of Julius Caesar's invasion of Britain - an ancient fort scattered with human skulls and weapons.

Alice discovers the well-preserved writing tablets, swords and domestic items left by Romans at Vindolanda during a time of British rebellion. On the Scottish island of Iona, there are traces of a long-lost monastery and pilgrimage site that was originally built by the legendary saint Columba, and has been compared to Jerusalem. In the east of Scotland, a weapons hoard belonging to a wealthy Bronze Age warrior is unearthed.

In this special, Professor Alice Roberts reveals the forgotten story of the Roman Army's secret weapon in Britain - their cavalry. These fearsome horsemen were the key to defending Britain's most famous Roman monument fortification, Hadrian's Wall.