The UN cultural agency Sunday designated Hamburg's historic maritime warehouse and business districts, boasting early 20th century German brick architecture, as World Heritage sites.

The "Speicherstadt", the world's largest historic warehouse complex, is a district of connecting roads, canals and bridges dating from 1885 to 1927, lined with red-brick office buildings.

Covering 26 hectares (64 acres) in the heart of the northern German city's bustling port area, its Gothic red-brick warehouses once stored high-value goods, such as coffee, spices and tobacco, UNESCO said.

As well as its architecture, it has more recently become a centre for tourism in Germany's second biggest city, as well as a draw for innovative businesses or eateries.

Opposite stands the "Kontorhaus" office district in Hamburg's old town, built in the 1920s and 1930s, which UNESCO also listed at its meeting in the German city of Bonn Sunday.

It includes the "Chilehaus" which resembles a ship's bow and, according to UNESCO, "represents the most significant artistic and architectural achievement of German Brick Expressionism".

"It strongly influenced brick architecture of the 1920s and 1930s in Northern Europe and is also one of Germany’s first high-rise buildings," it said in a statement.

The Chilehaus was built between 1922 and 1924 by Fritz Hoeger.

UNESCO's World Heritage Committee said the two districts were examples that "illustrate significant stages in human history".