For 10 years now, an empty streetcar has rolled silently through the streets of Warsaw on January 27. Instead of a route number, it has a large Star of David on the roof. Its route takes it through the part of the city that Poland's Nazi occupiers turned into Europe's largest Jewish ghetto in 1940.

The journey of this empty streetcar is a reminder of the Warsaw Jews murdered during World War II. Before Nazi Germany's persecution and killing of Jewish citizens, there were 330,000 Jews in Warsaw — a third of the capital's population. After New York, Warsaw was home to the second-largest Jewish community in the world.

The main remembrance ceremonies commemorating the victims of the Holocaust are held at the former Auschwitz concentration camp in southern Poland. About 1.1 million people were murdered at Auschwitz, the Nazi's biggest extermination camp, between 1940 and 1945. Over 90% of them were Jews from Poland and other Nazi-occupied countries in Europe.

Auschwitz was liberated by the Soviet Red Army on January 27, 1945. Since 2005, this day has been commemorated around the world every year on International Holocaust Remembrance Day .

Of the 6 million Jewish victims of the Holocaust, the vast majority were killed in occupied Poland, which is why many Jews continue to regard Poland as a large cemetery.

A place of huge historical significance

Franciszek Bojanczyk is often asked by foreign visitors how is it possible for a Jew to live in Poland today. Even though some of Bojanczyk's ancestors were killed in the Holocaust, the 30-year-old historian said he would never leave Warsaw.

"When I walk through the streets of Warsaw, I sometimes reflect on what happened here," he told DW. "But not all the time. If I were to think every day about how tragic this place is, I couldn't live here. You can't think about death all the time."

Since the beginning of the year, Bojanczyk has been responsible for Jewish diaspora communications at the POLIN Museum of the History of Polish Jews in Warsaw.

Jewish story 'swept under the carpet'

His wife, Zofia Bojanczyk, also works at the museum. She, too, has Jewish roots.

Her mother's family converted to Catholicism several generations ago. "At home, many of my parents' Jewish friends regularly came to visit, although we never marked any religious celebrations," she said. Nevertheless, she is familiar with Jewish life. "It's not like I had to go and discover it, or it was something that came as a surprise to me."

Her grandfather escaped extermination during the Holocaust. "He was adopted at a very early age by Polish parents, grew up in a Polish house, was baptized and is a devout Catholic," she said.

Unfortunately, she said, her family doesn't like talking about it. "This story is kind of swept under the carpet," she told DW. She hopes to stop it being forgotten altogether and explore it with her father in the future.

Searching for their Jewish roots

It's not unusual in Poland for people to only discover their Jewish roots when they begin exploring their family history. After the Holocaust, many Polish Jewish families tried to keep knowledge of the horrendous fate of their ancestors from the younger generation.

When Franciszek started getting interested in Jewish history at school, his mother shared the memories of her grandfather, a Holocaust survivor, with him. Until then, he had no idea he had Jewish roots.

"In the notes of my great-grandfather, Tadeusz Neuman, I discovered an assimilated family that identified as Polish," he told DW. The Neumans didn't go to the synagogue and were baptized before the war broke out. When the German occupiers forced all Warsaw Jews into the ghetto, the family managed to escape this fate.

Remembering the appalling fate of Europe's Jews

Tadeusz Neuman, who trained as an architect at the University of Munich, held senior positions in Polish industry before the war. His wife, Zuzanna Goldfeder, was a niece of the famous French carmaker Andre Citroen.

For years, the affluent family was able to obtain new papers, pay for hiding places or bribe the Gestapo, the Nazis' secret police. Neuman and his son survived. Goldfeder, however, was arrested by the Gestapo in 1942 and forced into the ghetto, where she was shot dead.

"Perhaps it happened here, or very close to the place I now work," said Franciszek pensively. The imposing building that houses the POLIN Museum stands on the site of the former ghetto, near the "Umschlagplatz," the place where Nazi troops rounded up hundreds of thousands of Jews before sending them to the death camps.

"But I also think of the people who built a new life on the ruins," he said.

Almost 3.5 million Jews lived in Poland before World War II, making up 10% of the Polish population. Just over 400,000 survived the Holocaust.

Most of them left the country after the war — among other things because of the pogroms and antisemitic campaigns of the Polish Communists.

The collapse of communism in 1989 was followed by a revival of Jewish communities. Today, it's estimated that about 20,000 people in Poland have Jewish roots.

'A friendly place for Jewish people'

Franciszek Bojanczyk said Jews can feel safe in Poland. "Luckily, Poland doesn't have the kind of dramatic antisemitic incidents like the ones in Paris or the US that remind us of the prewar years, like the daubing of Stars of David on doors," he said.

He added that while there has of late been an increase in antisemitic and anti-Israeli slogans on the Internet — above all because of the war in Gaza — Poland is still "a friendly place for Jewish people."

Zofia and Franciszek are looking to the future with hope, and plan to tell their 2-year-old son directly about his roots. "I want to give him a Jewish upbringing, which I never had, so that it's natural to him — so that he doesn't have to dig deep into his memory to find it, or find out about it by chance," said Zofia.

Just like the Bojanczyks, many young Poles with Jewish roots are exploring their identity and hope that both in private and in public, difficult Jewish-Polish issues will no longer be seen as taboo.

This article was originally written in German.