All 10,344 window panes of the John Hancock Tower needed to be replaced because of poor glass integrity.

Location: Boston, Massachusetts

Cost: $175 million

Constructed: 1968-1976

Issue: Flexibility and poor glass integrity

Date of incident: 1973

As the tallest building in Boston, the John Hancock Tower (now simply known as 200 Clarendon Street) was mired in controversy even before it was built.

Initial plans showed that it would cast a shadow over Trinity Church, leading to public outcry and a quick redesign of the building. Despite this effort, the building continued to trouble the public.

During construction, the blue reflective glass used for the building started to fall off from various heights, forcing police to close off the area around the building. Subsequent research in wind tunnels identified additional integrity issues, such as twisting in high-power winds.

The real issue, though, was that the building expanded and contracted wildly due to differences in temperature inside and outside of the building. The reflective material caused the glass to be stiffer than expected, and instead of absorbing motion, it transferred it and simply shook out of place.

All 10,344 window panes were replaced by single-paned, heat-treated panels, helping inflate the cost of the project. During the time it took to identify and fix the problem, sheets of plywood replaced many of the missing panes, earning the nickname "Plywood Palace."