San Francisco wasn't always the perfect geographic rectangle we know today. Originally the Financial District was a cove, North Beach was an honest-to-god beach, and the Marina District was a placid swamp lapping at the shores of Cow Hollow. Aside from Ocean Beach and the Presidio, the only section of the city's shoreline still intact from the pre-bayfill days is the short strip of real estate between Aquatic Park and Fort Mason. After paying your respects to the Municipal Pier fisherfolk and taking in the unparalleled views of the bay, Alcatraz, and the Marin Headlands, trudge up the long curved walkway to the west. Note the prevalence of native plant life and the wild, rocky, wildflowered shoreline below. This is essential San Francisco in its feral, formative state, as when the hills were covered with sand and scrub and the bay dominated the peninsula instead of the other way around.