LOS ANGELES — The most notorious new house in Los Angeles hangs from a Bel Air hillside, high above the sprawl and smog, unfinished and unloved.

Outraged neighbors call it “the Starship Enterprise,” and in truth it looks like nothing so much as an earthbound space station of curved glass and steel, draped in scaffolding and tarpaulin, roughly 30,000 square feet and nearly 70 feet high.

That height, about twice the legal limit, is among a litany of violations that have stalled construction at 901 Strada Vecchia for more than a year. Without the city’s permission, workers tore down the original house and leveled the hillside. Though the site is in an “earthquake-induced landslide area,” subsequent inspections found “unsecured open excavations” and other perils. Inspectors also uncovered a host of features, unapproved though befitting a house with an aspirational price tag of $100 million, among them underground bedrooms and an IMAX theater.

As unapologetically extravagant as the project is its impresario — Mohamed Hadid, father of the celebrity models Gigi and Bella Hadid, sometime guest on “The Real Housewives of Beverly Hills” and one of the city’s leading luxury developers. For years, Mr. Hadid’s Instagram account has featured photos of himself amid the rebar at the Bel Air site. He calls it his “office” and labels the photos with the hashtag #themodernhouseofhadid.