Administrative Courtyard, Balboa Park. Beautiful. Inexpensive (just a park permit ~$275) and private. Be warned, airplanes do fly overhead. If that's a deal-breaker for you, don't have your ceremony here. In October for a 3pm ceremony, we only had one airplane fly over during the ceremony. When the plane flew over, we paused (because it's loud) and then continued about 30 seconds later. Really not a big deal and such a gorgeous location that we didn't care.
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