Blaenavon - "Pwll du" Tram tunnel. 1780-1812. 2400mtres Horse drawn
Guanajuato- The subterranean Roads. The first was built in 1883-1908 other followed in 1960s, 70s etc
Semmering - Semmering tunnel 1431 mtres 1848-54
Budapest - Underground Railway 1893-6
Vatican/Rome "Passetto di Borgo" 1277 - 800 metres Connects Vatican with Castel Sant'Angelo for Popes to escape!!
There must be more. Again to avoid lisiting every pedestrian underpass the tunnel should preferably be mentioned in the documentation or be "significant. The former is true of all the above other than the Passetto - there was probably just too much else to mention. I think it is "significant" enough.