A fortress the size of a small farm sits on a rise outside Elvas, and it is easy to ride past without noticing it. The Fortlet of Sao Mamede is one of the smaller pieces in the great defensive puzzle of this border town, an outpost on high ground whose job was to hold an approach and make life hard for anyone trying to besiege the main walls. It dates from the seventeenth century, the age of the Portuguese Restoration wars, when the country was fighting for independence from Spain and every hill on the border sprouted earthworks, a time when engineers sketched star-shaped plans from Dutch and Italian pattern books.
What makes these small works fascinating is how they fit together. Elvas was not defended by one wall but by a system: a main bastioned enceinte around the town, two big forts on hills outside, and a ring of smaller works placed to cover the gaps, all arranged so that their guns supported each other. A besieger who took one position found himself under fire from the next. It was a layered defence, planned like a game of chess, and the UNESCO listing in 2012 recognises the town and its forts as a single whole.
The fortlet is just outside the old town, about a kilometre away, in a landscape of olive trees, stone walls and fields. A rider can reach it by a short ride from the centre of Elvas along country lanes that are narrow, sometimes rough and often shared with a tractor or a flock of sheep. Elvas, about ten thousand people, has fuel, food and repairs, and the roads around it are mostly quiet.
Alentejo summers are fierce. Between June and September the sun hammers the plain and the heat shimmers off the tarmac, so ride early, carry water, and take lunch in the shade. Spring is the sweetest season, with wildflowers in the verges and storks feeding their young on the roofs, and autumn brings mild afternoons.
While you are here, find a cafe in the old town and ask for a slice of sericaia with plums, the baked egg pudding that Elvas has made its own.