the hike closest to SF

You may know about hikes in Marin and East Bay, but one small mountain is only 10 minutes away from San Francisco: San Bruno Mountain.
The California State Park maintains this location that can get an amazing view of San Francisco and the entire Bay Area on a clear day. This area is home to several species of endangered plans and butterflies.
The facilities includes parking, bathrooms, picnic tables and of course, plenty of trails.
Location/Directions (per state park website):
From Highway 101, take the Bayshore Boulavard/Brisbane exit. Continue on Bayshore Boulavard to Guadalupe Canyon Parkway. Turn west on Guadalupe Canyon Parkway toward the Mountain and go to the park entrance.
From Highway 280, take the Mission Street exit. Go north on Mission Street to Market Street. Turn right on Market street and proceed northeast. At Guadalupe Canyon Parkway, turn right and go eastbound to the park entrance.

