Acueducto de los Milagros

Listen first. Somewhere above you, there is a dry, rattling sound, like wooden sticks knocked together. Look up to the tops of the granite piers. Those are white storks, clapping their beaks from their huge nests of twigs. Below them, the stone is warm and rough, grey blocks striped with bands of red brick. You are standing beneath the Acueducto de los Milagros, the Aqueduct of the Miracles, in Mérida, in western Spain.

To understand why this structure exists, we need to go back to the city's birth. Mérida began as a Roman colony called Augusta Emerita, founded in 25 BCE under the emperor Augustus. Its first settlers were veteran soldiers, the emeriti, men who had finished their service in the wars in northern Spain. The name of the modern city comes from that Latin word. Augusta Emerita grew into the capital of Lusitania, a Roman province that covered much of present-day Portugal and western Spain.

A Roman city of this size needed water. A great deal of it. Water for public fountains, for the baths, for private houses of the wealthy, and for latrines that were flushed with running channels. The Romans did not like to rely only on wells. So they built long water channels that ran from reservoirs in the hills, sloping gently all the way into town. This aqueduct is one surviving section of that system.

The water for this line came from the north, from a reservoir known today as Proserpina. That reservoir sits behind a Roman dam, a few kilometres away, and remarkably, the dam still holds water today. From there, the channel travelled mostly underground or at ground level. Only here, where the land drops into the shallow valley of the Albarregas river, did the engineers need to lift the channel high into the air on arches.

That is the key idea behind every Roman aqueduct. The water moved by gravity alone. There were no pumps. The channel had to fall very slightly, mile after mile, without ever rising. When a valley interrupted that line, the builders did not let the water dip down and climb back up. Instead, they carried the channel straight across on a bridge of stone. What you see in front of you is that bridge, with the water channel once running along its very top.

Now look closely at how it is built. The piers are made of large granite blocks, cut into neat rectangles. Between the stone courses, you can see thick horizontal bands of red brick. This mix of stone and brick is a Roman technique, and it gives the structure its striped appearance. The brick layers helped to level each stage of the work, and they added some flexibility. The contrast of grey and red changes with the light through the day.

The arches stand in more than one level. Tall piers rise from the ground, and smaller arches link them together at different heights, like the rungs of a giant ladder. Many of the piers also have sloping buttresses on their sides, which helped to brace them. Some arches have fallen over the centuries, and the line now has gaps. Yet a long stretch still stands, several storeys tall, marching across the valley floor.

Here is the first surprise. The exact date of this aqueduct is still discussed by historians. It is often linked to the early centuries of the Roman city, but scholars do not fully agree on when it was built, and it was probably repaired and changed over time. So when you look at these stones, you may be looking at work from more than one generation of Roman builders, not a single grand project finished in one go.

And the name? It is not Roman at all. Long after the empire fell, the aqueduct stopped carrying water and slowly began to decay. People of Mérida, in later centuries, looked at these tall piers still standing in the fields and found it hard to believe they had survived. According to popular tradition, they called them the miracles, los milagros. It is a name of wonder, given by neighbours, not by engineers.

The second surprise is right above your head. The storks are not a decoration. They have made the tops of these piers their home, and they return each year to the same huge nests. Some nests sit on almost every high point of the structure. In spring, you may hear the young birds and see the adults flying in with food. For many people in Mérida, the aqueduct and the storks are now part of one picture.

This aqueduct is one part of a much larger set of Roman remains in Mérida. The whole archaeological ensemble of the city has been on the UNESCO World Heritage list since 1993. Across town you can find a Roman theatre, an amphitheatre, a long bridge over the Guadiana river, and the remains of a circus where chariots once raced. Mérida is one of the places in Europe where the outline of a Roman city is still easy to read.

Take a moment to walk along the path beside the arches. The ground here is green, with grass and trees along the small Albarregas river. People from the city come here to walk dogs, to jog, and to sit on benches in the shade. Close by, you may also notice a small Roman bridge over the same river. These everyday scenes sit side by side with stones that are close to two thousand years old.

If you stand at one end and look along the line of piers, you can follow the path the water once took toward the city. Imagine a steady stream running high above, quiet and covered, crossing the valley day and night. Down here, people walked, traded, and herded animals beneath it. The aqueduct was not a monument to them. It was simply part of the plumbing of a busy Roman town.

Before you leave, look up one more time. Notice the line where the grey granite meets the red brick. Notice the gaps where arches once stood, and the storks turning slowly in the sky above the piers. Listen again for that dry clapping sound. As you walk away, turn back once. From a distance, the arches look light, almost like lace against the sky. That is how they have looked to people here for many centuries.