After a pedestrian in Manhattan was fatally struck by a piece of building facade, officials this month conducted surprise inspections that determined that 220 other buildings in the city had serious violations that their owners had failed to address, the authorities said on Monday.

The Class 1 facade violations — which can include cracks in a facade, missing bricks or loose masonry — were considered so dangerous that they posed a threat to the public and required the building owner to immediately put in place protections for pedestrians, a spokeswoman for the city’s Department of Buildings said.

The inspection sweep came after the death this month of a New York architect, Erica L. Tishman, who was walking on the southeast corner of Seventh Avenue and 49th Street, near her office, when falling debris struck her in the head.

The debris had come from 729 Seventh Avenue, a 17-story office building in Midtown with retail shops on the first floor, according to the Department of Buildings. In April, the owner of the building had been fined by the city because terra cotta above the 15th floor was coming apart and at risk of falling.