To what should lanyards be attached while climbing?

When climbing an antenna tower, fall-arrest lanyards must always be attached to the tower legs. The vertical legs are the strongest structural components of the tower, designed to support massive loads and withstand the sheer forces of a fall. Attaching a lanyard to horizontal elements like tower rungs or cross-bracing is extremely dangerous. These parts are designed primarily to keep the legs in position or support a static climber's weight; they are not engineered to survive the sudden dynamic shock load of a falling person and may snap under the stress. Similarly, antenna masts and guy brackets are meant for specific mechanical purposes related to the antenna system itself. Always trust your life to the main load-bearing vertical structures of the tower.