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.
Robert Smithson and other so-called land artists simply disengaged from architecture, placing their works in America's open landscape, leaving behind the museums and galleries Smithson referred to as "tombs". A new "expanded field" allowed artists to contextualize their work beyond the institutional frame of the museum or the commercial structure of a gallery. Richard Serra, who also began to move outdoors, at times chose to "attack" architecture, creating structures that disrupted or overwhelmed the buildings around them.
The artists of the Light and Space movement took another tack. Rather than fight or flee the architecture, they explored and manipulated it, approaching architecture as a kind of found object, creating a series of rooms that incorporated architecture and architectural structures directly into their art. Bruce Nauman summarized it well: "When you work in a gallery or museum, the architecture is a given. If you wanted to have a show, you didn't have a choice, except to deal with it. You had to find a way to either absorb architecture into the piece of build your own."