TV Guide for Tomorrow Wednesday 26 in BBC Four

Chris Beardshaw travels by helicopter to find Britain's most inspirational garden. She goes to South West Ireland, where exotic plants grow outside.

Technical developments are enabling us to see the world of plants in ever greater detail, giving us insights into their remarkable abilities to adapt and survive.

Dan Snow reveals how the Irish saved Britain from cultural oblivion in the Dark Ages. He examines the demise of civilisation in Britain after the Romans left.

Ben Robinson discovers some of the impressive and well-preserved lime kilns in Solva, Wales, and learns how this industry helped feed a growing nation.

Autumnal fog and an overheating engine prove to be problems for narrowboater Robbie Cumming as he navigates a Roman waterway and a tidal river.

Simon Sebag Montefiore charts Rome's rise to become the capital of western Christendom and its impact on the lives of its citizens, elites and high priests.

Mary tackles the biggest puzzle of all: why, and how, did the Roman Empire fall.

Acclaimed historical drama. As Caligula's erratic behaviour continues, many in the Praetorian Guard come to realise that something needs to be done. Deals with adult themes.

Drama series chronicling the reigns of four Roman emperors. The mad Caligula is assassinated, and Claudius is proclaimed emperor by the Praetorian Guard.

How the growing number of European arrivals in Tasmania saw the death count grow, too. Contains some violence and some upsetting scenes.

Simon Sebag Montefiore charts Rome's rise to become the capital of western Christendom and its impact on the lives of its citizens, elites and high priests.

Mary tackles the biggest puzzle of all: why, and how, did the Roman Empire fall.