Construction cranes are everywhere in these days of a booming construction market. In many cities they dominate the urban skyline.
Cranes provide a majestic view of the cityscape to the urban adventurer. For this reason, they are often the target of climbers. Construction crews are well aware of this, and take numerous measures to prevent crane climbing.
If climbing a construction crane is in your future, expect fences (often with barbed wire), plywood cages around the base of the crane, bright lights illuminating the infiltration areas, private security patrols, padlocks, and other countermeasures.
All of these can be overcome by the experienced adventurer, but it takes patience and planning. The view is well worth it.