best concert venue

The best hall I've ever heard is the Concertgebouw in Amsterdam, then the Musikvereinn in Vienna.
In this continent I would say Jordan Hall in Boston for chamber music, and Carnegie Hall is still magical overall.

The Opera House in Sydney, Australia is acoustically outstanding. The views are also fine from anywhere.

The Greek Theater in Berkeley, California.

The Mondavi Arts Center at UC Davis (CA) is phenomenal.

And I still get the chills remembering the sound of the diva at the Kirov, in Leningrad (St. Petersburg). That is one humbling theater.

Kiev Philharmonic Concert Hall, Ukraine.
Only 500 seating. Choir sometimes is being placed on surrounding balcony while the orchestra is on the stage.
The stage is quite small as well. This venue is considered to be an ideal one for unamplified performance.
Another cool one that I realy like is Irridium Jazz Club where the most music you realy hear from the live instrument rather than it's amplified.