Michael Portillo is on Northern Ireland's spectacular Causeway Coast to begin a railway journey that takes him along the north and east coasts of Ireland through the provinces of Ulster and Leinster.

Beginning on the windswept shores of Loch Foyle, he investigates the 17th-century origins of Ireland's sectarian divide, braves choppy seas to join an archaeological expedition, meets local teenagers learning about their costal home, and surveys the spectacular basalt landscape of the Giant's Causeway.

Michael Portillo is in Bangor, County Down, en route to the Northern Irish capital, Belfast. Admiring the handsome waterfront houses, he recalls the resort's prosperity after the railways arrived and learns how local groups are launching a cultural revival.

He learns about the history of Stormont and the Good Friday Agreement, explores the regenerated waterfront on the Maritime Mile, visits the largest coastal inlet in the British Isles, and discovers a scheme to generate power with a tidal kite.