Along the Carrer de les Carretes, a narrow, dingy street in Barcelona’s Raval neighborhood, the ghost of Franco jumped out at me.

Calle de las Carretas, the sign said. It was smudged and faint, tacked onto a forgotten wall in a forgotten alley mostly populated by Pakistani immigrants. I wondered how many of them noticed the sign in Spanish — the tangible legacy of fascism, a time when Franco’s regime violently suppressed the local Catalan language.

Nearly every place name in Barcelona, the hub of Spain’s Catalonia region, is written in Catalan, which most natives have spoken among themselves for centuries. But from the Civil War of the late 1930s until Franco’s death in 1975, Castilian Spanish was a law laid down with such hateful force that many Catalans today would rather spit than speak it.

Peaceful rallies demanding Catalan independence are a result of that time. But Calle de las Carretas tells another version of the story — as does a wall a few blocks east, in the medieval quarter, where Hebrew inscriptions etched more than 500 years ago speak to the persistence of Sephardic memory.

I thought of those walls last weekend, amid horrific images of neo-Nazis marching with torches, swastikas and a 1924 monument to Confederate General Robert E. Lee in Charlottesville, Va. I thought about what it really means to “cherish our history” — the president’s loaded phrase following the episode — versus cherishing the opportunity to bear witness to our history, a different matter altogether, and one with special resonance for Jews.

Activists and protesters gesture at a man wearing a confederate flag before a KKK rally in Charlottesville, Virginia on July 8, 2017. Getty Images

As travelers wandering the world, we often do cherish the historical artifacts that remain to be viewed and interpreted. Jewish heritage throughout the diaspora is often visible only in these remnants.

But if Charlottesville — and Barcelona — offer any lesson to the traveler, it is that such artifacts must be considered, thoughtfully and sensitively, in the context of both their own historical provenance and what came afterward.

To offer an obvious example, when we visit the Nazi death camp that is now a state museum at Auschwitz-Birkenau, it is certainly not the history itself we cherish. It is the opportunity to bear witness — to stand on the same ground where a terrible history happened. Visitors must “behave with the appropriate solemnity and respect,” according to museum rules.

Those bleak barracks, and the others preserved throughout Central Europe, would be unbearable to contemplate if not for the significant modern-day efforts of both Polish and German societies to do the right thing, to officially renounce anti-Semitism and to stand firmly with Israel. By consensus, there is no ambiguity surrounding those historical sites.

When I was 12, my family stayed in New Market, Va., about an hour from Charlottesville, en route to the Shenandoah Valley Civil War battlefield memorials. My indelible memory is of a picturesque Southern town bedecked with fresh, new Confederate flags — “as if,” I thought to myself, “the North had never won the war.”

That impression held a powerful lesson. Perhaps because I grew up with daguerreotypes of Union soldier ancestors in the family album, it remains the strongest, strangest memory out of all my trips through Virginia.

New Market’s Confederate symbols were deliberate. But sometimes, as in Catalonia, history gets left there by mistake. That was the impression Oggi had in Nettuno, a town south of Rome, where a statue of the first-century Emperor Nero lords over the beachfront.

Historians debate whether Nero was a true or fair-weather friend of the Jews, a Jewish convert, a mass murderer or a callous musician who fiddled while Rome burned (centuries pre-violin, this last is a historical impossibility). But of all the people Rome might honor with prime real estate, Oggi found Nero an odd choice.

Even odder are the massive monuments of Communist heroes littered across the post-Soviet landscape of Eastern Europe. Like many Westerners, I have a guilt-inducing, voyeuristic fascination with that Cold War iconography: the skyward gazes, mustaches and raised fists.

Seeing such artifacts in their original locations is undeniably powerful. And however controversial the associations, as a traveler I have always appreciated the way such vestiges prompt us to consider the tangible history in our midst.

But the thoughtful, well-publicized speech by New Orleans Mayor Mitch Landrieu, explaining why his city recently took down Confederate monuments, enlightened many of us to nuances of context and provenance.

To appreciate history is to note the critical distinction between legitimate artifacts of a cruel past, like Franco’s signage, and tributes planted later on with a political agenda, such as monuments to the nation-threatening Confederacy erected more than 50 years later in New Orleans and Charlottesville.

Then there is the approach taken by artists in downtown Sofia, Bulgaria, where the Soviet-era Red Army monument has lately been more of a climbing toy for children than a rallying point for Stalinists.

A few years ago, an ironic trickster painted over the entire statue: one soldier became Superman, another Santa Claus, another Batman’s Joker. The erstwhile Communist heroes are a more popular sight than ever — but the joke’s on them.