1) for engineering/economic reasons. it couldnt have been built across the river,
in any arch shape, because the river is 3 times wider than the current base

2) besides, it was designed as the "gateway to the west". if it went across the
river it wouldve been a gateway to the north/south. this "gateway" commemorates
the westward expansion of the US into indigenous territory, so of course its a
racist monument by current standards.

3) its base equals its height, 630 feet, but it gives the illusion of being taller
because of its mathematics, which do not describe a parabola, as commonly stated,
but rather a "weighted catenary"

4) it is considered outstanding 1960s space age design, but its plans were submitted
for a 1947 competition

5) my favorite fact: each leg needed to be constructed individually, but the legs needed
to meet up at the top within 1/64 of an inch. this was widely considered impossible, and
why it took 4 years to construct, with constant tiny adjustments to the gigantic pieces