Not all the towers along a transmission line are identical. Look closely at a tower where the line makes a sharp turn and you will likely find it is wider and beefier than other towers along the route. The added strength and weight are needed to resist the unbalanced pull of the conductors, which might overturn an ordinary tower. These special towers are called deviation or angle towers.
The transmission-line tower everybody knows is an Erector Set latticework of steel girders and diagonal braces. The techniques for designing and building these towers are the same ones used in constructing steel bridge trusses or crane booms. The individual pieces can be made cheaply from rolled steel and then bolted together on the site. This last point is more important than it might seem: transporting a fully assembled tower 100 feet tall is an awkward and expensive business.
When poet William Blake wrote of "dark satanic mills", he couldn't have been looking at a steel mill because there were none in 1804. Nevertheless, when I visit a steel mill, Blake's phrase always comes to mind. With the heat and the pounding noise, the dust and smoke, and the red glow against the night sky, it's hard not to see these places as infernal. And yet the process of making steel also produces some of the most hauntingly beautiful images found anywhere in the world of industry.
As a practical matter, I think it's easier to see ugliness than to imagine beauty. Most of the people who've made beautiful things seem to have done it by fixing something that they thought ugly. Great work usually seems to happen because someone sees something and thinks, I could do better than that.