The Vía Verde de la Sierra among the vultures' cliffs, in Andalusia

In the Andalusian interior, between the provinces of Cádiz and Seville, runs a railway that never saw a train pass. Built largely in the 1920s and then never put into service, its track bed lay there for decades until it was transformed into one of Spain's most spectacular greenways, the Vía Verde de la Sierra. To cycle it is to cross limestone gorges, viaducts and tunnels in a sierra landscape where griffon vultures wheel above the cliffs.

The itinerary

The route links Puerto Serrano, on the Cádiz side, to Olvera, one of the famous pueblos blancos perched with its castle and church dominating the valley. Between the two endpoints the greenway winds along the watercourse, passes through numerous tunnels carved into the rock, many of them lit, and crosses viaducts that span the canyons. The most famous stretch is that of the Peñón de Zaframagón, a great limestone crag that hosts one of the most important griffon-vulture colonies in Andalusia: nearby there's an observation centre from which to follow the vultures in flight. Along the track, the old stations of the line that never opened have been restored and turned into welcome and refreshment points, a detail that gives this route its distinctive character.

The route

The surface is the typical one of a greenway on a railway bed: even and with gentle gradients, because railways don't like steep climbs. This makes the route accessible even to those without great training, while remaining a sierra route through a wild environment. The tunnels, some of them long, are an integral part of the experience, and the lit ones are ridden through without problems. A touring or gravel bike is suitable; it's worth checking in advance the state of the tunnel lighting and carrying a backup light anyway.

To get there, the reference points are the city of Seville, with its airport, and to a lesser extent Cádiz and the coast, from which you reach the interior by car. This is the area of the Sierra de Cádiz, the domain of the pueblos blancos, and Olvera in particular is a finale worth a dedicated visit, among white alleyways and views over the valley.

When to go

The best period is broad and, unusually, includes the winter months: roughly from March to November, with the most pleasant windows in the shoulder seasons and even in the depths of winter. Southern Spain enjoys a mild climate, and while much of Europe is under the rain, here you can cycle in the sun in agreeable temperatures. The Andalusian summer, by contrast, can be scorching and is best avoided during the central hours. Precisely because many people think of cycling as a summer activity, this route stays quiet in the cold months, when the climate is ideal and the sierra is silent: it's one of those rare routes that give their best out of season.

The surroundings

Around the greenway there's a whole world to explore. The Sierra de Cádiz is the land of the pueblos blancos, the white villages perched on the heights, and beyond Olvera it's worth casting your gaze towards the other villages of the area, among olive groves, vineyards and limestone profiles. The Andalusian cuisine of the interior, made of cheeses, cured meats and rustic dishes, is an excellent travelling companion, and the restored stations along the track often offer the chance to sample it. It's a route that lends itself to both sporty cycling and slow travel, to be savoured over several days.

A practical tip: plan a stop at the observation point of the Peñón de Zaframagón and bring binoculars, because seeing the griffon vultures soar over the limestone walls is the most memorable moment of the day. And take advantage of the old station-refuges along the track to break up the journey: stopping to eat in the station of a railway that never worked is exactly the kind of story that makes this route special.