In a black-and-white photo, visitors can make out the Führer saluting the crowd from the chancellery window on the evening of January 30, 1933, after earlier having been made chancellor and been charged by president Paul von Hindenburg with forming a new government.
The picture is on display at "Berlin 1933. On the Path to Dictatorship", due to be opened by Merkel in the German capital on Wednesday, on a site charged with history as the former headquarters of the Gestapo, the secret police of the Nazi regime.
It now houses The Topography of Terror, an open-air documentation centre whose exhibition will trace Hitler's first months in power through photos, newspapers and posters.
"The hour has come! We are at Wilhelmstrasse (the site of the chancellery at the time). Hitler is chancellor of the Reich. Like in a fairytale," wrote Joseph Goebbels, who was to become Nazi propaganda chief, in his diary on January 31, 1933.
Posters go on to show images of the Reichstag going up in flames the following month and then the first measures taken against the Jews on April 1, with the start of a boycott of Jewish shops, doctors and lawyers.
"Germans, defend yourselves! Don't buy from Jews," a poster states.
Andreas Nachama, director of The Topography of Terror, said the arrival of the failed painter from Austria at the helm of power in Germany was an "incision" in history, although nobody at the time thought he would last.
However the parliamentary system of the Weimar Republic failed to find a stable majority and Hitler, on the back of over-simplified themes, rallied millions of unemployed and people who had lost everything in the economic crisis.
According to Nachama, the exhibition shows the "daily erosion of democratic institutions" as the Nazi regime began to build up steam, eventually leading to World War II and the deaths of 40 to 60 million people, including six million Jews.
The 80th anniversary has sparked much interest in Germany - a novel that imagines Hitler's return to modern-day Berlin entitled "He's Back" (Er Ist Wieder Da) has become a bestseller here.
Another two exhibitions are also due to open - one on Berlin and the Nazis at the German Historical Museum and the other offering a thematic tour of Berlin's symbolic sites from the Third Reich.
Just ahead of the anniversary, Merkel said in her weekly podcast that Germany had "an everlasting responsibility for the crimes of National Socialism, for the victims of World War II, and above all, for the Holocaust".
"We're facing our history, we're not hiding anything, we're not repressing anything. We must confront this to make sure we are a good and trustworthy partner in the future, as we already are today, thankfully," Merkel said.