Checkpoint Charlie was arguably the most famous crossing point between East and West Berlin. It became the scene of a chilling standoff between US and Soviet forces in October 1961, which ended without a single shot fired. Years later, it was revealed that Karl-Heinz Kurras, a West Berlin police officer and undercover spy, had passed information about US troops to the Soviets at the time.

Glienicke Bridge was another legendary border crossing between East Germany and West Berlin. On several occasions, captured Soviet and Western spies were exchanged here, giving it its nickname "Bridge of Spies." A 2015 Steven Spielberg movie of the same name retells this fascinating history.

East Germany's notorious spy and surveillance agency, the State Security Ministry, colloquially known as the Stasi, was housed in a nondescript building in East Berlin. Today, the former spy headquarters is open to visitors, with many offices and conference rooms preserved in, or restored to, their original state — including East German spy chief Erich Mielke's phones (pictured).

Many people who fled East Germany found shelter at West Berlin's Marienfelde Refugee Center. Over the decades, the center took in some 1.3 million refugees. Arrivals wishing to stay were screened by Allied intelligence services who wanted to learn potential secrets about East Germany and the Soviet Union.

Perched on a mountain of World War II rubble, the former Teufelsberg listening post is worth a visit. Located in Berlin's verdant Grunewald district, the site was built in the 1960s by the US National Security Agency (NSA) to spy on the Eastern bloc. Today, visitors can take tours of the eerie ruins.

The Allied Museum is located in Berlin's Zehlendorf district, in what was once the American sector. Free to visit, it recounts the tense Cold War era from the perspective of the Western Allies, i.e. the US, France and Britain. One highlight is a section of a spy tunnel secretly built by the Americans and British to tap into Soviet communications.

You'll find the German spy museum situated near Potsdamer Platz, where the Berlin wall once split the city in two. It showcases a wide array of fascinating espionage gadgets used throughout the ages up until the recent past. It also shines light on Berlin's legacy as a spy city. Featuring many interactive exhibits, the museum is a great place for kids and grown-ups alike.

In 2019, the newly built headquarters of Germany's foreign intelligence agency, the Bundesnachrichtendienst (BND), was inaugurated in central Berlin. The imposing complex houses some 3,000 staffers tasked with gathering political, economic and military intelligence about foreign targets. Surprisingly, and despite all this secrecy, the BND headquarters has a visitor center.

Both Russia and Ukraine trace their cultural ancestry to the Kyivan Rus period in the early Middle Ages, when a loose federation of Slavic, Baltic and Finnic peoples formed a common identity. Missionaries from the Germanic peoples were eventually replaced by diplomats. This painting, depicting the Baptism of Prince Vladimir — or Volodymyr — in 987, hangs in Kyiv Cathedral.

Russia was under Mongolian rule in the late Middle Ages, but lively trade with the Hanseatic German cities continued. The period began with a victory over Teutonic knights in the so-called Battle on the Ice on a frozen lake in 1242. Sergei Eisenstein turned the battle into a patriotic Russian epic in the run-up to World War II.

Born in what is now Szczecin, then in Prussia, Catherine the Great acceded to the Russian throne in 1762, after the overthrow of her husband, also born in Germany. Her reign oversaw the Russian Enlightenment, whose intellectual ideals — freedom, liberty, and reason — she championed. Those ideals did not extend to Poland, however, which she partitioned with Prussia.

Like many of Europe's colonial monarchies, Prussia and Russia found common cause in opposing revolutionary France and the military campaign of Napoleon Bonaparte. The alliance was sealed at the Convention of Tauroggen in 1812 between a Prussian general and a German-born general of the Russian Imperial Army, in which many Prussian soldiers served.

In 1913, Kaiser Wilhelm II (right) invited his cousin Czar Nicholas II to Berlin for the wedding of his daughter. A year later, the two countries were at war, and four years later, both men had lost their thrones, with Nicholas executed in 1918. Millions of Russians and Germans were killed in the war, and both countries felt aggrieved by the terms imposed by the Western Allies.

Represented by foreign ministers Joachim von Ribbentrop (left) and Vyacheslav Molotov, Adolf Hitler and Joseph Stalin (right) signed a non-aggression pact in August 1939. The following month, both countries invaded Poland. Germany tore up the pact in 1941 with the invasion of the Soviet Union known as Operation Barbarossa. Nearly 14 million Russians and 6.8 million Ukrainians died during the war.

East Germany fell under the Soviet Union's influence after the war, an alliance that found its iconic image in the "socialist fraternal kiss" between German Democratic Republic leader Erich Honecker and Soviet leader Leonid Brezhnev in 1979. East Germans grew up learning Russian and until today many have more understanding and sympathy for the Russians and their President Putin than West Germans.

Chancellor Willy Brandt tried to normalize relations with the communist nations during his tenure from 1969 to 1974, a rapprochement that became known as "Ostpolitik." In 1970, Brandt (center left) signed the Moscow Treaty alongside Russian Premier Alexei Kosygin (center right), which formally recognized East Germany and temporarily abandoned the goal of German reunification in exchange for peace.

"Gorbi, Gorbi!" was the jubilant headline of Germany's mass-circulation Bild tabloid in June 1989 when Soviet leader Mikhail Gorbachev came to visit. For Germans he was — and still is — the hero who made the peaceful unification of the country possible.

German-Russian relations developed throughout the post-Soviet years, with German Chancellors Gerhard Schröder and Angela Merkel hoping that deepening trade ties would bind the countries together and soften Russia's authoritarian leader Vladimir Putin. Schröder initiated the Nord Stream pipeline project, which many believe left Germany dependent on Russian gas.