The Philharmonie in Berlin is an early example (perhaps even the earliest?) of a modern concert hall with the orchestra in the middle and the audience seated in irregular blocks on all sides. It was built from 1956 to 1963 by the architect Hans Scharoun (1893-1972).
The German author Gerwin Zohlen, in an article on the architecture of the Philharmonie for one of their program booklets, pointed out that in those days there was no such thing as CAD (Computer Aided Design), so Scharoun was dependent on “brigades of draughtsmen who had to render the sketches and drawings he’d dashed off with a thick 3b pencil into measurements and proportions”. The tools they had for this task were “a T-square with ruler and sharpened pencil, a compass and measuring tape“ — to which I would add that they had their slide rules for calculations. (Recall that for most of the 20th century, vocational schools routinely offered courses in “mechanical drawing”.)
According to Zohlen, “Scharoun thought radically from within a building, not from its exterior, particularly when it came to the Philharmonie.“ To me, this helps to explain why the shape of the outer walls seems almost accidental: after planning everything from the inside out, he simply added whatever outer walls were necessary to enclose it all.

Seating in the Philharmonie
This sort of seating arrangement has often been imitated (and refined) in later concert halls. It has the effect of bringing the audience closer to the orchestra, and also seems to enhance the acoustics, though Scharoun — like later architects — also enlisted the help of acoustic experts when finalizing his design.
I must admit that I have mixed feelings about Scharoun. Judging from the Philharmonie, he was doubtless a brilliant architect who was well ahead of his time. But he was also a dreadful urbanist who wanted to tear down everything that was still standing in Berlin after the Second World War and completely rebuild the city within a huge grid of highways separated according to living, working, administration and cultural functions. Zohlen describes this as “a nightmare scenario from today’s perspective, though with this vision Scharoun in no way stood alone.”
Indeed, Scharoun’s plan for Berlin was similar to what Le Corbusier had proposed for Paris in the 1930s: tear down the old city and replace it with high-rise buildings connected by a system of motorways.
Scharoun was not a Nazi, as far as I know, and not even a Nazi sympathizer like Le Corbusier. Although he stayed in Germany during the twelve years of Nazi rule, he kept a low profile, designed private houses and avoided any involvement in Nazi architecture. For this reason, the allies chose him to head the municipal planning office in Berlin after the war.
(I’ll have more to say about Scharoun when I get around to posting things about the German cities of Kassel and Leipzig, but that might take a while.)

Stairs in the Philharmonie
In 2003 I attended a marvelous concert at the Philharmonie, featuring the dramatic symphony Roméo et Juliette by Hector Berlioz (1803-1869), played by the Berlin Philharmonic Orchestra conducted by Sir Simon Rattle, with three singers including the mezzo-soprano Angelika Kirchschlager.

Bus 200 at the Philharmonie
In 2005 I took a guided tour of the Philharmonie. The tour was free at that time, but now (as of 2017) it costs five Euros (or three Euros for students, unemployed, retired and disabled persons). Tours begin daily at 13:30 (aka 1:30 pm), and tickets go on sale at 12 noon. (Advance reservations are not possible.)
On our tour, we learned that the sections of the hall directly in back of the orchestra, facing the conductor, are always the first ones to be sold out when Sir Simon Rattle is conducting.
My photos in this post are from 2005. I revised the text in 2017.
See also: Brahms in the new Concert House in Copenhagen.
Another great post, Don. I always learn something new from your writings.
Leslie
I paid to sit facing the orchestra here at the Pops when Matthew Garbutt was the conductor. He enjoyed his work so well it showed by the swaying of the tails of his tux.