There's a haunted quality to the Presidio's decaying coastal bunkers, a twisted, rusty, fog-shrouded Weltschmerz of abandonment and eerie quietude. They were built a century ago to protect the Golden Gate from a succession of encroaching enemies; now grass grows in their cracked armor. The bunkers were dismantled before the end of World War II; the Presidio came under the aegis of the National Park Service eight years ago. Today there are cafes, educational facilities, and other peaceful endeavors in the adjacent woods and meadows, and in the spring the bluffs bloom with poppies, lupine, and Indian paintbrush. But the old gun batteries are visceral reminders of another season, particularly mournful when the mist is settling and phantoms are afoot.