I checked it for you:
The length of the boom is assembled by workers on the ground, and it is 4-5 meters long. The base of the tower crane, its own lifting system, the cab of the tower crane, the boom and the heavy truck crane are installed in place. Later, the height of the tower crane will increase with the rise of the building. Use your own boom to lift a certain height, use your own lifting system to lift the driver's roof, and the workers will install the section to be lifted above the original height, below the driver's building, and so on. This is also the way to lower yourself when you fall. Each section is about 4 meters long. When the tower crane reaches a certain height, it will be connected with the building for many times to enhance the stability of the tower crane.
The tower of a tower crane is built by a crane. This crane has a strange shape, which is slightly wider and higher than the sectional structure of the tower. Every time a tower body is added, the tower body is separated from top to bottom, and a segmented structure is added from the middle to improve the tower body.
After the tower is erected, the boom and counterweight are cable-stayed.