Nothing to do with Telly Savalas. The Khojak Tunnel (a.k.a. Sheilla Bagh Tunnel) is a 3.91 km long railway tunnel constructed in 1891 under the Khojak Pass in the Killa Abdullah district of Balochistan, near the Pakistan-Afghan border at Chamman, 1,945 metres above sea level.
The tunnel remains one of the longest tunnels in South Asia, and the longest in Pakistan (expected to be surpassed by the 8.6 km Lowari Tunnel, currently under construction). The turrets on the portal in the early scenes were removed at some point. More here