Corona Heights is a 13-acre park built on a former brick quarry, and the exposed red chert rock at the summit gives it a raw, almost lunar quality that feels nothing like the manicured parks elsewhere in the city. Steps lead up to an unguarded hilltop with panoramic views from downtown to Twin Peaks -- without the tour buses or crowds you get at more famous viewpoints.
The Randall Museum, a small free natural history museum aimed at kids, sits at the base of the hill. The park is popular with dog walkers and hawks circle the thermals above the exposed rock. A good stop if you are walking between the Castro and the Haight.