Mount Snowdon was located at the Snowdonia national park. (PROSE: Death of the Doctor)
Clive Finch travelled to Mount Snowdon with his mates Jacko and Bean because they believed an alien spacecraft had once crash landed there. (PROSE: Rose)
A team from Torchwood One dug up the remains of an alien spacecraft buried at the foot of Mount Snowdon and found Magna-Clamps buried there. (TV: Army of Ghosts)
The Immortality Gate was found in a ship that had crashed at the foot of Snowdon. It was also recovered by the Torchwood Institute. (TV: The End of Time)
UNIT Base 5 was built into Mount Snowdon. (TV: Death of the Doctor)