DALLAS — Dallas Mayor Tom Leppert is sending a strong message to landlords who own vacant buildings: Clean up or pay up.

They face fines of thousands of dollars if found with filthy and dangerous structures.

Mayor Leppert said such properties constitute both a safety issue and a health hazard.

"In some of these buildings, it is just so bad that you can't send anybody in," he said. "The smell — all the other issues from an environmental standpoint — we don't want to send our people back in them again."

Bird droppings cover the entire fourth floor of the downtown Statler Hilton, once considered the nation's model of modern hotel design.

The vacant structure, which dates back to 1956, was just added to the Preservation Dallas list of endangered historic buildings. The group's director, Katherine Seale, was saddened by the deplorable conditions.

"We are very supportive of any or all efforts to encourage these property owners to sell the building or fix it up," she said.

Seven landlords identified by city officials now have 30 days to repair or sell their properties. Otherwise, they face a fine of $1,000 a day for maintaining an illegal dump.

E-mail ddenmon@wfaa.com