The tony town of Hillsborough is suing the owner of one of its most well-known landmarks — the so-called Flintstone House — over gaudy outdoor decorations and other work, including a herd of large dinosaur sculptures and a sign reading, “Yabba Dabba Doo.”

Attorneys representing the ultra-rich Peninsula enclave filed the lawsuit in San Mateo County Superior Court against the home’s owner, Florence Fang. The town said the additions were installed without proper permits and “create a highly visible eyesore and are out of keeping with community standards.”

Fang, a well-known Bay Area businesswoman, philanthropist and former publisher of the San Francisco Examiner, purchased the iconic home in 2017 and soon began adding the patina-covered dinos and other gaudy outdoor improvements.

The multi-domed home at 45 Berryessa Way is perched on a hillside visible from Interstate 280 and overlooks Lower Crystal Springs Reservoir. The bizarre abode is praised by some and maligned by others for its unconventional design by Bay Area architect William Nicholson. It was constructed in the mid-1970s by spraying concrete over a wire mesh and steel frame.

Fang’s modifications also included a retaining wall, steps, columns, gates, a parking strip, and a deck for social gatherings, Mark Hudak, the attorney for Hillsborough, wrote in the lawsuit. Several of these improvements “created live-safety hazards that required immediate correction to protect visitors to the property,” he said.

Fang did the work without planning approvals or building permits “except for a very limited permit for a low wall in the front of the property,” Hudak wrote.

The town’s building department issued a stop-work order in December 2017, followed by a second notice in January 2018. The building department issued a third notice in August.

Fang was cited for multiple violations last year, and the town’s Administrative Hearing Panel issued a order calling the home a public nuisance. In October, the panel ordered the decorations removed by December and hit Fang with a $200 penalty.

Fang did not challenge the order, making the decision final, Hudak said, but the improvements remain, prompting the town to sue.

Efforts to reach Fang were unsuccessful.

Evan Sernoffsky is a San Francisco Chronicle staff writer. Email: esernoffsky@sfchronicle.com Twitter: @EvanSernoffsky