In the Hollywood Hills, where musician and studio owner Jed Leiber lives, his imposing 12,000-square-foot house is known by some locals as “the Fortress.”

The walls are made of concrete. High-resolution security cameras monitor activity. Each room requires a key fob for access. And the master-bedroom suite includes a safe room, built into one of two dressing areas and hidden by a bulletproof plate that slides down from the ceiling.

Mr. Leiber, son of the late songwriter Jerry Leiber and owner of NightBird Recording Studios in West Hollywood, bought the house in 2012 for $7.2 million, primarily for its Bauhaus -style architecture and a sweeping view of Los Angeles, which has moved him to call it “Sky Castle.” Since then, he has also come to value the property’s strong security and has further upgraded it.

“I just want to make sure that anyone is safe within the walls of my home, Sky Castle,” says Mr. Leiber, who wants to spend more time traveling and touring and is seeking $50 million for the seven-bedroom, 12-bathroom house. He also owns a penthouse apartment in West Hollywood.

High-end homeowners are increasingly taking James Bond-esque security measures to manage threats ranging from burglars and kidnappers to terror attacks and civil unrest. Such precautions can cost millions, but as prices for home technology come down, sophisticated security systems are showing up in middle-class homes as well.