Golden Horn Bridge
by EdChamberlain, published
You can now purchase this model from shape ways! https://www.shapeways.com/model/2174934/golden-horn-bridge.html?modelId=2174934&materialId=28
Designed by Leonardo Da Vinci in 1502 for Ottoman Sultan Beyazid II of Constantinople, the bridge was intended to span an inlet known as the Golden Horn. Construction was never perused because it was deemed impossible to build.
Print and remove structural material. You shouldn't need much support under the arc bit.