Usually, monuments commemorate the heroes of a nation. Berlin's Holocaust Memorial is the exact opposite. In a newspaper interview published in 2011, renowned German writer Martin Walser called it "the first monument erected by a nation in memory of its crimes." Thousands of people visit every day. It is open to the public and can be accessed around the clock.

During World War II, the Nazis killed six million Jews - an extermination considered the worst crime in history. According to Martin Walser, the Holocaust memorial "matches the crime it commemorates: It's a gigantic monument." Amazingly, it is also "a beautiful construction, a work of art." The bright lights in the background belong to Potsdamer Platz.

In summer 1998, a model of the memorial was presented at Brandenburg Gate. As a result of a competition, four designs had been chosen, including the "field of stelae" conceived by American architect Peter Eisenman. The concept found favor with then-Chancellor Helmut Kohl who, from then on, advocated the construction of the monument.

The basic concept of the Holocaust Memorial was mooted on August 24, 1988, during a panel discussion in West Berlin. Journalist Lea Rosh proposes to erect a monument at this "site of perpetrators". Without her dedication, the monument would not exist. The picture shows Rosh delivering a speech marking the symbolic beginning of the monument's construction in January, 2000.

Erecting the enormous monument in the center of Berlin, between the Reichstag, Brandenburg Gate, and Potsdam Square, was a mammoth task that took several years. 2,710 concrete slabs, or stelae, were arranged symmetrically on 19,000 square meters (4.7 acres) of land. All of them have identical base measurements, but different heights. The total cost amounted to about 27 million euros.

The central monument commemorating the killing of Jews in Germany has developed into a tourist attraction. Year after year, hundreds of thousands of visitors dip into the sea of cement pillars - mostly young people from all over the world. The Holocaust Memorial is one of the most visited sites in Germany's capital.

The monument's information and musem center is located underneath the memorial and complements the abstract form of remembrance represented by the monument. The permanent exhibition gives names and faces to the victims, portraying the fate of individuals and their families, their lives, their suffering, their deaths. Drastic images are rare - the horrors can be imagined in the visitor's mind.

The deeper visitors enter the rippling maze, the stronger their feeling of existential loneliness: they don't know where to go. Although in the center of Berlin, they are far, far away from everything. All of a sudden, one gets an eerie feeling of loneliness, of desertion and threat. Such was probably the experience made by most of the victims during the Holocaust - albeit much more terrifying.

The Memorial's architect, Peter Eisenman (82), is delighted that his monument has been so well received. Children play hide-and-seek here, young people take "selfies" and couples kiss - he likes it all. He didn't want to create a "sacred place", he says. He is also pleased with the abstract nature of the monument: "You're neither reminded of a death camp, nor of anything equally horrible."

"You can't arrange the way people remember the Holocaust," says Eisenman. Some bring flowers, some pray, some sit on the slabs. Playing, laughing, contemplating: in Berlin everyone can make up their own mind about how they want to commemorate. That many visitors are clueless about the Holocaust does not bother Eisenman. The monument is always open, and free - as is remembrance.