Why are the tops of cell phone towers always triangular? Is there something special about this design? Here is a picture of a tower on fire (just to spice things up) that shows the triangle shape at the tower top.
I believe it is for efficiency. The triangular shape is the cheapest (requires least material) to provide structural integrity. (Think about if they made it an octagon)
They’re triangular because they have three sets of antennae pointing in three different directions. The different levels of antennae are because more than one company is using the same tower. The only thing I’m not sure about if one tower serves only one cell or if it serves three cells. I’m sure someone out there knows.
As far as unusual cell towers go, see the one near the bottom of the howstuffworks page on cell towers. As they say, that’s one tall, ugly tree.
The cells of cellular telephony are often arranged in a hexagonal lattice with these triangular antennas at alternating corners, as shown here, with one antenna for each of the three cells.
This is not the only way that cells can be arranged. Along interstates in rural areas, for example, you often see towers with only two sets of antennas; here the provider has decided to cover only the area along the road, so the cells are just arranged in a line along the highway.