Rusted Weapons Outside a City

For art, a really cool painting will be one of a modern city, filled with white building of cool design with blue windows as a background. You know, like those cool modern ones. In the front will be a field of brown rusty old medieval weapons and armor. Between the buildings and the rust field will be a grass field.

In the Rusty field, everything will be the same brownish rust color with some variation. ex add black and stuff. The outline of the weapons will be black. A prominent thing in the field will be a helmet . Also there should be a spear/pike with a pennant on it.

The city will be all skyline and there will be no square buildings. The whole painting is meant to represent change. I think that the best medium for this would be paint although don't know what type. Definitely not watercolor.