In my more youthful days this was called "Buildering", as opposed to "Bouldering" (ie. selection of some inanimate object to practice one's climbing prowess on).
It has beeen reported in other articles that he would sometimes stop his car when he saw a tower cuz he just had to climb it.20 years ago in the construction industry Iron workers would be all over the structure without any safety harnesses, walking I beams and such, it gets in their blood.