Trans-Iranian Railway

From the Caspian Sea to the Persian Gulf, the Trans-Iranian Railway crosses two mountain ranges, four climatic zones and 1,394 kilometres of rivers, highlands, forests and plains. Built between 1927 and 1938 by the Iranian government with 43 contractors from many countries — and financed through national taxes to keep foreign control out — the line demanded 174 large bridges, 186 small ones and 224 tunnels, 11 of them spiral. UNESCO inscribed the railway in 2021.