No other city in America can claim a national park within limits, so running at San Francisco's Presidio is a must. Dozens of trails wind around this lush coastal bluff area nestled under the Golden Gate Bridge. Head straight up to the observation point for a lung-busting hill workout and gorgeous views of the Bay Area. Or, hit up the 2.7-mile section of the California Coastal Trail (connecting Baker Beach and the Golden Gate), part of a longer 1,200-mile route that hugs the coast from Mexico to Oregon.
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