Photographer David Clifford has captured the world's most dogged runners doing what they love in the most remote and unforgiving environments.
The idea behind this quirky new tour of Lisbon is to see the city with new eyes, by, erm... closing them. Instead of relying upon sight to explore the delights of the Portuguese capital, you're encouraged to wear a blindfold and to drink in the smells, the sounds, the tastes and the very feel of the Alfama district, instead: the distant strains of Fado music here, the smell of cinnamon pastries there... you get the idea.
The original aim of the tour was to help to break down preconceptions about blind people by trying to recreate their experience. It is led by a blind guide and member of the local Acapo (Association for the Visually Impaired), with various sighted assistants on hand to stop you from stumbling down any flights of stairs.