One afternoon last week, I escorted Wojtek Smolen, a lanky, 32-year-old visitor from Oswiecim, Poland, on his first walk around the city. Mr. Smolen wanted to see Chinatown, so we strolled the length of Canal Street. Dressed in jeans, a black turtleneck sweater, and desert boots, my guest could have passed for a New Yorker – until he gazed up in puzzlement at the fire escape of an old building. “What is that?” he asked. No fire escapes in Poland, apparently.

My guest surely already knew what I only then realized: A good guide must never take something for granted that could puzzle a visitor. Mr. Smolen is head of the 160-member guide staff at the State Museum at Auschwitz, located on the premises of the vast and infamous Nazi concentration camp. The camp is on the outskirts of the small city of Oswiecim, the Polish name for Auschwitz, an hour’s drive west of Krakow.

Today is the 60th anniversary of the liberation of Auschwitz by the Red Army in 1945. To mark the occasion, Mr. Smolen was invited to America on a two-week lecture tour by the Jewish Foundation for the Righteous, a privately funded organization that provides stipends to rescuers of Jews in 15 countries and also does educational outreach.

Until 2003, an average of 500,000 visitors toured Auschwitz annually, Mr. Smolen said over lunch at Great N.Y. Noodletown, where he expertly manipulated chopsticks and even showed some English tourists at the next table how to use them. In 2004, the number of visitors jumped to about 600,000. “That was when Poland joined the European Union,” he said. “Other E.U. citizens could then enter without visas.” The largest numbers of foreign visitors to Auschwitz come from America, Germany, the U.K., and Israel, according to Mr. Smolen, who lectures mainly in English. But Polish visitors have always been in the majority. All Polish students are required to make at least one visit to a concentration camp as a history lesson, although parents, rather than the government, must foot the bill. “Most of our student groups come from big cities, where families are likely to have more money,” Mr. Smolen said. “We get more visitors from Gdansk, which is 400 miles away, than we do from villages near the camp.” Students are not considered ready to visit the camp before age 14.

On my own first visit to the “mother camp” in 1977, I gaped at the enormous piles of suitcases, shoes, eyeglasses, and prosthetics on display. I saw a small crematorium, the gallows, and the “Black Wall” against which countless prisoners were shot. But I didn’t realize that a short distance away from the mother camp, on a swampy plain, was Birkenau, the far larger camp with its massive killing machinery. “Back then, there probably weren’t any taxis then even if you’d known to go there,” Mr. Smolen said when I told him about my ignorance of Birkeanu.

On a guided tour during my third visit to the camp I took 10 years ago, explanations had changed for the better. The guide precisely explained the different ways that Jews and non-Jews were treated by the Germans. Only non-Jews, for example, had their “mug shots” taken, while only Jews were subject to the selection that led most of them to the gas chamber. Museum guides now routinely make study trips to Yad Vashem, Israel’s Holocaust museum and memorial in Jerusalem. Staffers from Yad Vashem also study at Auschwitz. Mr. Smolen twice attended seminars at Yad Vashem, the most recent in 2001. He often guides Israeli groups visiting Auschwitz. “Almost every Israeli had some Polish relatives,” he said. “When our former president Lech Walesa addressed the Israeli Knesset, he spoke in Polish. Many legislators understood him.”

Mr. Smolen’s father, Kazimierz Smolen, survived four years as a political prisoner at Auschwitz. The elder Mr. Smolen was a longtime director of the State Museum at Auschwitz, established in 1947 as a monument to Nazi criminality. Wojtek, born in 1972, grew up a short distance from the camp. “The museum was part of my life,” he said. “I followed tour groups around and read books about what happened here. But I didn’t think that it would be my future. While I was studying biology at Jagiellonian University in Krakow, I began guiding at Auschwitz. And I never stopped.”

The history of Auschwitz is complicated. Its first use as a concentration camp in 1940 was to incarcerate Polish political prisoners. Russian prisoners of war began arriving in 1941, and the first convoys of deported Jews came in the winter of 1942. By then, Birkenau was being built a little more than a mile from the “mother camp.” Almost a mile long, it was surrounded by an electrified barbed wire fence strung from concrete poles. At Birkenau’s center, by mid-1943, were capacious underground gas chambers to be dedicated to Jewish mass murder. Above them, in innocent looking brick buildings with roof dormers, were banks of high-speed ovens. Able-bodied deportees selected for work were housed in endless rows of wooden barracks, each originally designed for the German army as a stable for 54 horses.

“Before the Germans abandoned the camp,” Mr. Smolen said, “they wanted to obliterate all traces of their crimes. Luckily, they had neither the time nor the resources to do that.” While the gas chamber and crematoria were dynamited, their ruins remain a palpable presence.

After an interview, museum-guide candidates must attend a six-month course taught by scholars from both the Auschwitz state museum and Jagiellonian University. “Everything ends with a written exam that takes several hours,” Mr. Smolen said. “It’s serious stuff. If you pass that, you walk around the camp with a group of examiners for a practicum. If you’re forgetful or don’t explain things clearly, you don’t pass. Also, candidates may know their history well, but if they put their own politics into their presentation, or make extreme statements, they fail.”

On the day before Mr. Smolen and I toured Chinatown, I sat in on a class he gave to city high-school teachers at the New York Tolerance Center on East 42nd Street. Calmly, clearly, he laid out the gruesome facts and set straight some commonly misconceptions about Auschwitz. Tattooing of prisoners on the left arm, for example, was a procedure developed not to “turn a person into a number” but rather to address the problem of how to “identify corpses as they piled up.” When non-Jewish prisoners died, camp authorities issued a death certificate to the family. “For a payment,” Mr. Smolen said, “the family even had the right to receive the ashes. Of course, it probably wouldn’t be the actual ashes of that person.” Prisoners would often be killed by an injection of a chemical directly into the heart – “one of the more humane ways of killing a prisoner in the eyes of the camp doctors,” according to Mr. Smolen.

Although teachers in the class were uncomfortable listening to Mr. Smolen detail the atrocities of Auschwitz, his tone was matter-of-fact. After the class, I commented on his own lack of emotion as he lectured. “We guides try to present the history of the camp, that’s all,” he said. “We let the visitors think for themselves. It’s enough to let them feel their own emotions.”