Gateway Arch
There is no other structure like it in the world.
630 feet tall, and 630 feet wide, it's a modified catenary inverted arch, and it supports it's full weight strictly on tension and compression.
There are a series of stairs on the inside for wizards, but the mortals can take the elevator, which is a unique design that self rotates as it moves up the path.
The entire structure is crafted from stainless steel, and it gleams in the sun.