The triangle is another example of a strong, durable structure. Like tubes, triangular structures are durable yet lightweight. They also use up little amounts of raw materials, which helps to save money. This is why triangular structures are used in all kinds of buildings and devices. For example, the roof of a house can be made out of triangular structures. This makes it more resistant to rainfall and snow storms than a flat roof. 

Even a rectangle can be turned into a durable structure if you add at least one triangular structure to it. 

Electricity poles can be built using triangular structures. Light posts and floodlights can likewise be built using triangular structures. This makes them durable and lightweight. 

The Eiffel Tower in Paris may well be the most famous building in the world. It uses triangular structures, which is why it is durable but uses only a relatively small amount of material. Crane lifts also make use of triangular structures.