Civilization Was Here

Remains of early Hydrocarbon Age river crossing, Perth. Submerged by rising sea level c. 2040. Image: East Scotland Underwater Survey, 2138.

... leave a call sign.
All the kings of the future will hear.
Civilization was here.
(Capercaillie)

My contribution to Marcus_Hediger's Minimalism / Civilization challenge. Thanks to him and Skeena for an interesting idea.