We run our fingers along a dusty wall made of thick cubes of rock, mortared together in the 2nd century BCE by Romans to protect what would become their first provincial capital outside of Italy—now known as Tarragona. Built upon and around for millennia, the ancient wall once surrounded just a garrison, then grew to surround a town, and now lines a cobblestone street where residents and shop-owners live their lives, continuing their part in the long trail of history. 

Outside of town, a vast, three-story Roman aqueduct crosses a ravine, still sturdy enough to walk on but no longer bringing water into the town. Now it simply pays testament to the engineering feats of the time—to design and build massive structures that were angled just so in order for water to flow at the right pace into the right place so a growing community could thrive. We cannot see where the aqueduct tunneled into the city, but we know that its remnants are there, like ancient arteries connected to a still-living body. 

Later, we overlook what remains of the Roman Circus—an oval track with grandstands for watching chariot races built a couple of centuries after the first wall. We can see the stone Circus walls stretching like long fingers along streets and disappearing into the stucco walls of 19th-century buildings, now sitting where the track used to be—four city blocks wide and eight blocks long, all the way to the city hall plaza.

Underground tunnels, which once housed the charioteers prior to racing, underlie everything. Recently they have been rediscovered, cleaned up (after 19th century shopkeepers drilled holes in the ground to dump their trash into the tunnels), and opened to the public. The Roman walls and tunnels are literally built into the foundations of the modern city, popping out here and there where we can view them from the street.

Of course, it’s not just 19th- and 20th-century buildings that sit atop of and intertwine with Roman ruins here. Everything builds on what came before. The Romans built on (and often used materials from) the Iberian structures that dotted this peninsula before them. The Visigoths (post-Empire invaders from Germany) built cathedrals on top of Roman construction; the Moors (Musliim invaders from North Africa) built great new mosques, forts, and palaces in the same places; the Spanish Christians (descendants of the Iberians) built cathedrals on top of the mosques after driving out the Moors. Jews, longtime residents of the peninsula, built their own more modest temples, which were transformed into cathedrals when they, too, were driven out by the Inquisition. 

And it doesn’t stop there. We stood in one stone palace in Valencia that had been a glamorous center of commerce in the 1500s and later became a dour prison and “death row” for political prisoners during Franco’s fascist dictatorship in the mid-20th century. Sometimes all of this repurposing of the past seems like spiteful desecration; other times like practical incorporation. Either way, the idea of historical preservation seems to be a very recent innovation. 

The Roman amphitheater in Tarragona is a case in point. Built in the first and second centuries AD, this circular stone grandstand structure hosted a wide range of bloody entertainment for the masses—it could hold up to 15,000 spectators at each event—during its four centuries of use. In the middle of the arena stands the remaining square walls of a Visigothian church, built in the 4th century AD on the spot where Romans had martyred an early Christian leader, in order to sanctify, claim, and dominate this previously pagan space. In the 1500s, the church would become a convent, and then in the 1700s a prison, and then the whole structure fell into ruin before being rediscovered and restored more than 200 years later. Today, the restoration continues to unveil new tunnels, inscriptions, statues, and mosaics while shoring up crumbling stones, and we are able to join a handful of tourists to watch two modern-day “gladiators” demonstrate hand-to-hand combat (with protective padding) on dirt that was, two millennia ago, soaked in blood. 

On the southern coast, in El Campello (near Alicante), we found more evidence of cultures building upon previous cultures in the form of fish farms. We think of these as modern inventions, but in fact, there’s evidence linking holding pens carved out of coastal rock to Neolithic, Bronze Age, and Iberian settlements along the Mediterranean. Later, the Romans expanded on the practice they found there in order to better feed their growing population. We saw evidence of similar techniques in several places, and often these rectangular cut-outs continue to be used for fishing today.

Anyone who has visited Europe knows that the sense of historical time is vastly different than in the US. Our oldest structures are probably the Anasazi cave dwellings and Taos Pueblo (known as the oldest continuously inhabited town in the U.S.), both of which date back about 1000 years. Other than that, what do we have? Jamestown and Plymouth Plantation (facsimiles of structures from the 1600s)? The Paul Revere House (1700s)? 

Being able to walk around any street corner and see a still-in-use stone church built in the 1300s, stay overnight in a castle built in the 1100s, visit a mosque built in the 700s, stand on a wall built in 200 BCE—these opportunities just don’t exist in the States. To be fair: Spain has plenty of industrial cities, strip malls, highways, and high-rise towers. Yet there are also “old towns” in nearly every city we’ve visited, where this kind of tangible history is simply part of the fabric of everyday life.

In Tarragona, we stayed in an updated AirBnB apartment overlooking a public square with chairs and tables for a couple of cafes. Across the square was a tall, sand-colored stone wall, a bit pock-marked with age but thankfully unmarked by graffiti or fire escapes. It looked old, but we didn’t know until we later toured the Roman Circus that it is, in fact, part of the city walls built by the Romans in the first couple of hundred years AD. We toured it from the other side, but on this side of “our” little courtyard, it is just a wall like any other, except it’s two thousand years old. 

One sunny afternoon, we sat on some steps in the courtyard facing the wall as an older gentleman in a cotton jacket and fedora played Spanish guitar. We gave him our change, leaned back in the sun, and soaked it all in.