A window on the 36th floor of the tilting high-rise cracked last week and engineers have yet to determine a cause Millennium Tower must inspect all units and install a canopy around the perimeter of the 58-story building by Friday afternoon. The downtown tower has settled about 18 inches (45 centimeters) since it opened over a former landfill in 2009. Homeowners have filed multiple lawsuits against the developer and the city.