Built 128 years ago, in 1891, the Khojak Tunnel lies under the Khojak Pass, around 113 km from Quetta in Balochistan.
It is also known as the Shela Bagh tunnel and is a part of Sibi-Quetta-Chaman railway line.
It is 3.912 km in length and runs between the towns of Shela Bagh and Sanzala.
Khojak Tunnel was once the 4th longest tunnel in the world and still is the longest tunnel built in Pakistan.
Since its construction, the tunnel has been lit up using huge concave mirrors at the entrance; placed at an angle to reflect the sunlight into the tunnel.
The State Bank of Pakistan paid a tribute to this wonder of civil and mechanical engineering by printing its image on the now defunct 5 Rupee note.
The tunnel was visited by King Amanullah of Afghanistan along with his queen in 1927.
Khojak tunnel lies at an altitude of around 1,945 meters above sea level surrounded by beautiful panoramic views.
The temperatures are usually fairly low in the area with sheets of snow covering the ground in winters.
Picture Courtesy: Bheroze Amjad