Among the numerous traces of the French presence in the chinese southern province of Yunnan, neighbouring Viet-nam, the railroad linking Kunming to Hanoi is undoubtedly the most symbolic. After no more than four years of titanic construction works in the middle of a hostile jungle and impressive karstic landscapes of southeastern Yunnan, this railroad was inaugurated in 1910: twice destroyed, twice rebuilt, it has long been an essential lifeline for the development of Yunnan. Its construction was a one-of-a-kind challenge - over 60000 workers took part under extreme conditions, up to 12000 of them died; 3456 bridges were built, and 172 tunnels were pierced - which left us with an extraordinary heritage, to both the historical and technical extents; yet still little people know it besides the few lucky enough to have heard about it. The railroad is officially closed to passenger traffic since 2003, for security and profitability reasons. Only freight trains still ride its tortuous 465-kilometer long tracks, punctuated with engineering work-of-arts and remote stations in the typical French period architecture. Although talks of restoration have often been held, in particular to promote tourism around the railway, the closing to passenger traffic, as well as the current construction of a new moderne railraod to link Vietnam, question the future of this unique heritage. Adeline Cassier