Tatlins Tower

Tatlins Tower by Vladimir Tatlin, also known as the Third Monument to the Third Reich is one of the most re-known designs created in the constructivist era despite it never being built. It is said to be the monument which defines constructivism.
It was designed to be constructed from iron, glass and steel and was supposed to be 1312 ft.(Approximately 400m) tall becoming the tallest building/monument in the world.
The monument was designed to have a twin helix which would for the exterior structure which would allow visitors to travel from one section to another. Other than the twin helix the monument would consist of four different geometric forms which would each rotate at a different variance of speed.

The Cube:
The 'first sections' geometric structure would be the shape of cube. It was designed for business purposes such as meetings, lectures, conferences and would complete a 360 degree rotation once a year.
The Pyramid:
The Pyramid would be the 'second section' on top of the cube however it would be slightly smaller than the cube and would complete a full rotation once a month housing executive activities.
The Cylinder:
The next tier would be a cylinder which would complete a full rotation every 24 hours. The cylinder would house an information centre which would issue news bulletins and manifestos via loudspeakers, radios and a telegraph
Hemisphere:
The top tier would be an area for radio equipment.

The monument wasn't built because it is said there wasn't enough steel in the world to create it and if it was built then it's practicality is in question.

Personally this is number one on my list of inspirations and despite it's impracticality I would have loved to see the real thing. I love the geometrics of the design as well as the fact that the monument is both exposed and  concealed at the same time. It's form reminds me of a modern day roller-coaster and I think if it was built it would be one of the most visited structures in the world.