The Mantiqueira tunnel was located just outside Rio de Janeiro, in the lower regions of the Amazon Desert, at 51 degrees west by 16 degrees south.
In 2080, the Fifth Doctor and Turlough materialised the TARDIS in the north end of the tunnel to lie in wait for the train carrying Ileana de Santos, before quickly materialising on board as it went past. The Doctor described it as a dismal and dusty place. (AUDIO: Loups-Garoux)