power transmission /distribution line tower (ironman/electricity pylon called in Europe) is a tall steel structure, usually a hot dip galvanized steel lattice /angular tower, used to support an overhead power line cables.

They are used in high-voltage AC and DC systems, and come in a wide variety of shapes and sizes. Typical height ranges from 15 to 55 m (49 feet to 180 feet), though the tallest are the 370 m (1,214 feet) towers of a 2,700 m (8,858 feet) span.

There are four major categories of transmission towers:suspension, terminal, tension and transposition. Some transmission towers combine these basic functions.  The towers are usually steel lattices or trusses.The pressure drop of the angle steel plate is small, the gas phase flux is large, the plate efficiency is good, the structure is simple, the manufacturing&transportation is convenient and the rigidity is good. Although the area covered is larger than a single tubublar pole, but its stiffness is also slightly stronger than the single tube.

https://www.youtube.com/watch?v=rH4uQ9okJYA