The Los Angeles City Attorney’s Office has filed suit against one of the city’s most notorious supergraphic sign companies and 21 property owners for erecting a series of multistory vinyl ads around the city.

The defendants – Sky Tag Inc., its owner Michael McNeilly, and the property owners – face civil penalties of up to $2,500 per location for each day the ads were in place. The penalties potentially total in the tens of millions of dollars.

In court documents filed Friday, the city said that SkyTag deprived the city of permitting fees, created traffic hazards and endangered the lives of people inside buildings where the windows were covered by the ads.

Among the 17 locations identified in the lawsuit is a 12-story medical office building at 10921 Wilshire Blvd. in Westwood Village where Sky Tag displayed supergraphics advertising TV shows and consumer products. The city alleges that Sky Tag did not have permits for any of the signs and ignored multiple written notices ordering that the signs be removed.

The defendant property owner include WW Westwood LP, the medical office building’s owner; Beverly Blvd. Owner Co. LLC, owners of the Sofitel Hotel; and CIM Group, which owns a Hollywood office building at 1800 N. Highland Ave.

The Sky Tag lawsuit is the eighth civil enforcement action filed by the City Attorney’s Office since 2008 against outdoor advertising companies and property owners for erecting illegal, unpermitted and unsafe supergraphic signs.

McNeilly has been the most visible and vocal defenders of supergraphics, gaining notoriety in 2009 for installing huge images of the Statue of Liberty on office buildings in Hollywood, the Miracle Mile and the Westside.