ALCATRAZ ISLAND, Calif. —- For 150 years the lighthouse beacon here has alerted sailors to San Francisco's rocky, fog-shrouded coast. It beamed from the island when it housed a Civil War-era fort, a military prison, a maximum-security penitentiary and a national park.

Today, the public is free to roam the island's artillery batteries, prison cells and guardhouses —- virtually every building on the 22-acre island except its most recognizable structure, the towering lighthouse. The oldest on the West Coast, it has been under lock and key since 1854.

But that may change. The National Park Service is considering taking over five landmark Bay Area lighthouses from the U.S. Coast Guard and opening what aficionados call "American castles" to the public.

"Lighthouses punctuate our seascape," said Bob Trapani Jr., executive director of the American Lighthouse Foundation. "They strike a lot of emotional chords in a broad group of people. The sound, the night at light, that twinkle of light; if you grow up with that memory, it doesn't go away. Lighthouses are part of a romantic era, from a simpler time."