In a collection(2) of content items, each content item is represented by at least one signal for rendering in a perceptible form on a rendering system(5,6;25,26,27,28,29), and each content item is linked to data (8,10) specifying at least one geographical location for each content item. A method of providing access to the content items in the collection includes obtaining geographical data defining a route and assembling a signal for use by a 5 rendering system(5,6;25,26,27,28,29), the signal being representative of a succession of signals representing a sequence of content items, so as to progress along the route as the signals representing the sequence of content items are rendered. The content items in the sequence are selected by applying at locations along the route a selection criterion based on the location along the route and the data specifying at least one geographical location for 10 each content item. The signal for use by the rendering system, when rendered, causes a speed of progression along the route to vary according to how many content items are obtained for each next location along the route by applying the selection criterion, and according to the lengths of signals representing them.