Concrete rules.

Municipal Pier, Fort Mason.

As is clearly visible, the south side of the pier is crumbling and falling into the water, hence the railings down the middle, preventing access. The sea air attacks the steel rebar through the porous concrete, the resulting rust causes expansion and breaks up the concrete. If this neglect continues the whole thing is doomed.

Nikon D3x, 105mm pre-Ai MF Nikkor at f/5.6.