Berlin is the capital and largest city of the Federal Republic of Germany.

Administratively, Berlin also constitutes one of Germany’s 16 states.

Berlin became the capital of Germany in 1871, when the numerous independent kingdoms and principalities of Germany united to form a single nation-state. The city quickly developed into one of Europe’s major industrial and cultural centers and became the single most important city in Germany.

From 1945 until 1990, Berlin was a divided city. Following the defeat of the Nazi regime in World War II (1939-1945), the victorious Allied Powers — the United States, Britain, France, and the Union of Soviet Socialist Republics (USSR) — divided Germany into four zones, each occupied by one of the Allied Powers. They also divided Berlin, which was in the Soviet sector, into similar zones.

The Soviet-controlled sector of the city became known as East Berlin, and the Western-occupied sector became known as West Berlin.

In 1949, East Berlin became the capital of the German Democratic Republic (known as East Germany), one of two successor states established in Germany after the war. That same year the capital of West Germany, the other successor state, was established in the city of Bonn.

West Berlin remained an urban island surrounded by Communist East Germany. The city became a focus of Cold War tensions between Communist countries led by the USSR and anti-Communist states led by the United States.

In 1990, following the collapse of Communism in the USSR and East Germany, Germany was reunified, and a united Berlin was declared its capital. The government gradually began moving its offices from Bonn to Berlin, a process that was largely completed by early 2000.

In 1920, the old city merged with 8 towns, nearly 60 villages, and a number of surrounding farms and estates to form the current city boundaries.

Berlin’s city limits encompass the entire metropolitan area and include large areas of undeveloped land. Forests and farmlands cover nearly one-third of the city.

From reunification until 2001, the city was divided into 23 boroughs. In an effort to make urban government more efficient, an administrative reform that took effect in 2001 reduced the number of boroughs to 12.

At the heart of Berlin lies the medieval core of the city, located along the Western bank of the Spree River.

To the West of the medieval city is a formal grid of streets laid out on either side of Unter den Linden, a wide central avenue stretching from East to West and flanked with double rows of linden trees.

Before the postwar division of Berlin, this area, called the Mitte (city center), served as the administrative and financial center of Berlin and contained the main banks, publishing houses, large stores, the university, and government buildings.

Well-known streets crossing Unter den Linden are Friedrichstrasse and Wilhelmstrasse. The former royal park known as the Tiergarten occupies the land to the West of the Mitte district. Gradually, the city’s residential and industrial areas grew around the city center.

In the mid-19th century, a dense mass of tenements was erected to the North, East, and South of the central Mitte district. Known as Mietskasernen (rent barracks), these buildings were home to members of the working class who labored in nearby industrial plants.

In contrast, aristocrats and members of the middle class lived in the peripheral communities of that time (Dahlem, Grunewald, Köpenick).

Prior to World War II, Berlin contained many imposing buildings, many of them built after 1871, when Berlin became the German national capital. Much of old Berlin was devastated during World War II by Allied bombing raids and by fierce house-to-house fighting that occurred when Soviet troops captured the city in 1945 at the end of the war. Wartime destruction left the historic core of the city standing amidst 26 sq km (10 sq mi) of rubble.

The victorious Allies faced a daunting task in 1945. Berlin had lost almost three-quarters of its 1.5 million residential units. During the first two months of occupation, when the USSR held full sway over all of Berlin, the Soviet Army also dismantled and removed 67 percent of Berlin’s industrial capacity.

After the war, the boundary between East and West Berlin was drawn through the heart of the city. In 1961, the East German government encircled West Berlin with a fortified wall that traced the boundary. This wall was known as the Berlin Wall.

In the postwar redevelopment period, both East and West Berlin turned their backs on the wall and the area on either side of it, which remained a partially abandoned zone.