At his villa in Berlin's lush green Dahlem district, Gerstenberg's collection kept growing in the early part of the 20th century, with the spectrum of art ranging from Old Masters to the work of Impressionist painters like Renoir, Monet, Sisley and Degas.

There were also superb graphics, etchings and prints by Durer, Goya and Rembrandt, and lithographs by Honore Daumier, the French cartoonist and painter who delighted in satirising the bourgeois society of his day.

By the time he died in 1935, aged 87, Gerstenberg had amassed in his collection the almost entire lithographical oeuvre of Henri de Toulouse-Lautrec.

Then came World War II, and his treasured collection was stashed away in a city flak-bunker.

Seized by the Russians

Much of the collection was destroyed or seized by the Russian Army during the battle for Berlin in 1945. Hauled back to Russia as war booty, part of the collection has since 1995 been displayed in the Eremitage museum in St. Petersburg and Pushkin museum in Moscow.

In Berlin, what remained of the Gerstenberg collection was passed to his daughter Margarethe Scharf and, after her death, to her two sons, Walther and Dieter, where it became a starting point for their own art collections.

That they carried on the art tradition of their grandfather is illustrated by an extraordinary exhibition titled "Surreal Worlds" at the city's new "Scharf-Gerstenberg" museum, across the way from the imposing Charlottenburg Palace.

Named in tribute to Otto Gerstenberg, the Berlin exhibition owes much of its richness to the canny collecting skill of grandson Dieter Scharf.

Extending the collection

He upgraded the remainder of the earlier collection with exquisite examples of surrealistic art by Max Ernst, Salvador Dali and Rene Magritte, and with works by Odilon Redon, Paul Klee and Jean Dubuffet.

The Scharf-Gerstenberg show encompasses 300 works of "Surrealism and its Predecessors," and has created excitement with its spectacular examples of dark architectural prison scenes by Italian engraver Giovanni Battista Piranesi (1720-1778).

Julietta Scharf, a family descendent, who acts as president of the Gerstenberg art foundation, says the "Surreal Art" exhibits are not a present to Berlin, but are on a ten-year-loan, with conditions attached.

One of them being that they do not disappear into depots but remain on display on a permanent basis to the public.

Fragile paperwork

Two-thirds of the Scharf-Gerstenberg collection features fragile paperwork -- charcoal sketches, pencilled illustrations and collages. A small and beautiful 1953 Jean Dubuffet collage stems from butterfly's wings.

A stream of visitors have been arriving at the exhibition, with its heavy emphasis on surrealism, and drawings and collages by the likes of Hans Bellmer, Louis Soutter and Dubuffet.

The new Scharf-Gerstenberg Museum results from the transfer in 2005 of the famed Nofretete bust and the Egyptian Museum's papyrus collection from west to east to the city's famous "museum island."

This enabled architect Friedrich August Stueler's historic cluster of museum buildings near the Charlottenburg Palace to be redesigned for modern art purposes.

A museum city

Berlin now boasts 147 museums - almost double the number found in most other German cities.

Museum attendances have spiralled in Berlin in recent years, in contrast to most other German cities, where figure have been in decline in recent years.

In 2005, some 11.43 million people visited Berlin museums -- a surplus of more than 145,000 on the preceding year's figures, and attendances soared again in 2006-7.

Berlin's Wirtschaft (Economic) Magazine forecasts that this year city museum attendance will again rise, due to the city's Natural History museum, with its star (13.27-meter high) dinosaur skeleton attraction, reopening again after lengthy restoration.

Also, the Bode Museum in Berlin housing classical sculptures and antiquities, draws large crowds again on the Museum Island, after a 152-million-euro ($236-million) "face-lift."

"Everyone in Germany should at least one time in their lives pay a visit to the Museum Island in Berlin," the nation's Chancellor Angela Merkel observed not so long ago.

Art galleries galore

Not only do the number of museums carry on increasing in Berlin. Art galleries also multiply, with 380 galleries at last count, and more in the pipeline.

Werner Tammen, chairman of the city's Association of Berliner Galleries, claims Berlin has turned into a unique "melting pot" for the arts; one, "with enormous potential for the future of the city's cultural economy."

In that sense, Berlin has left London and New York trailing, he suggests.

But not all is sweet and honey. As a commercial art sales location "Berlin still has a bit of catching up to do," notes Tammen.