Short answers, pulled from the story.
Architect Max Meyer constructed the main building of Das Buddhistische Haus in 1924 under the direction of Paul Dahlke. Paul Dahlke was a German physician who commissioned this structure as his personal vision for Buddhism in Germany.
The Nazi government prohibited all Buddhist meetings and publications throughout Germany by 1941. Activities ceased entirely at the site following this governmental ban on religious expression.
Asoka Weeraratna bought the building from Dahlke's nephew in December 1957 on behalf of the German Dharmaduta Society trustees. This transaction marked the first time a Buddhist mission on German soil operated under Sri Lankan Sinhalese monks rather than Germans.
Visitors entering through the Elephant Door face seventy-three steps leading up to the main building. The interior houses a library and a dedicated meditation room for practitioners.
In 1959 the city of Nagoya donated a sculpture of Guanyin which now stands in the garden. About 5,000 people visited the public temple during the year 2006 alone.