Hey Daniel,
interesting place. These are often difficult to photograph as the combination of darkness and artificial lighting makes controlling hot spots almost impossible. You may have been better off going vertical in this case and concentrating on the center spires. Since you were at 30 seconds.....you could try placing your hand in front of the lens......burning in the brightest area. If you keep your hand very close to the lens, this should work just fine. Thanks for hsaring this cool lokking place with us!