[nutron5skills]

the whole thing with the weights which are located at the 58th floor not the 60th:

quoted from wiki

The building's upper-floor occupants suffered from motion sickness when the building swayed in the wind. To stabilize the movement, a device called a tuned mass damper was installed on the 58th floor. As described by Robert Campbell, architecture critic for the Boston Globe:

Two 300-ton weights sit at opposite ends of the 58th floor of the Hancock. Each weight is a box of steel, filled with lead, 17 feet (5.2 m) square by 3 feet (0.9 m) high. Each weight rests on a steel plate. The plate is covered with lubricant so the weight is free to slide. But the weight is attached to the steel frame of the building by means of springs and shock absorbers. When the Hancock sways, the weight tends to remain still... allowing the floor to slide underneath it. Then, as the springs and shocks take hold, they begin to tug the building back. The effect is like that of a gyroscope, stabilizing the tower. The reason there are two weights, instead of one, is so they can tug in opposite directions when the building twists. The cost of the damper was $3 million.

The John Hancock Tower seen from the Prudential Tower close to I-90, seen on the right
The John Hancock Tower seen from the Prudential Tower close to I-90, seen on the right

The dampers are free to move a few feet relative to the floor. LeMessurier Consultants says the dampers are located in relatively small utility rooms at each end of the building, leaving most of the 58th floor usable.

According to Robert Campbell, it was also discovered that—despite the mass damper—the building could have fallen over under a certain kind of wind loading. Ironically, it could tip over on one of its narrow edges, not its big flat sides. Some 1,500 tons of diagonal steel bracing were added to prevent this, costing $5 million.

it says they act as a gyroscope, just putting it out there not sure if anyone has mentioned this