Antoni Gaudi's architecture is among the world's most instantly recognisable sights. His still unfinished basilica, La Sagrada Familia welcomes five million visitors annually. Yet in this the centenary year of his death, knocked down in the street by a tram, mistaken for a tramp and spending his last hours in a paupers' hospital, much about this unworldly genius remains a mystery, not least the source of inspiration to create extraordinary buildings that stand in a place of honour of their own in the canon of architecture. His explanation - that the fount of his imagination was God - sits uncomfortably alongside his modern-day fame in a secular world that nonetheless celebrates him.

In reconnecting Gaudi's peerless architecture with the highs and lows of his faith, Peter Stanford walks in his footsteps through Barcelona, retracing his life through the buildings, parks and landscapes he admired and those that he created. Join him on Gaudi's journey from the Catalan countryside, where his love affair with nature began, to becoming a celebrated figure in the booming industrial city of Barcelona, with its extremes of rich and poor - and its undercurrent of violence and anti-clericalism that almost left La Sagrada Familia an unfinished folly. Tragedy, loss and depression stalked his life, but reinforced his belief that his work was a religious vocation, prompting contemporary moves by the Vatican towards declaring him a saint.