Unfortunately it was destroyed in 1970 by Kadhafi.
Quite impressive , shame it's gone, would have made a good Then & Now photo.
Trucks pass through 'Marble Arch', a monument built by Mussolini to mark the border between Cyrenaica and Tripolitania in Libya, 26 December 1942.
Some modern photos of the ruins of it.
L'arco dei Fileni de Mussolini
A interesting story behind it's location goes back to ancient history.
Mussolini's famous and expensive 'folly', the ‘Marble Arch,’with the two bronze figures representing the Phileni brothers from Carthage.
About 350 BC, a dispute over the boundary between Carthage and Cyrenica was to be settled by a foot race; two runners from Carthage running west while two from the Cyreneans ran east. The point at which they met was to be the boundary. The Phileni from Carthage were very much faster than the Cyrenean pair, and reached the point where, more than 2,000 years later, Musolini built his arch.
The Cyreneans objected that the new border had lost them too much of their land, and wanted men from Carthage to go back a bit. They refused. The Cyreneans finally agreed the border, but buried the Phileni brothers alive, and erected two altars to mark the graves. These became first, the agreed border, and much later, the site of Mussolini's Folly.
When we drove past it for the first time we we couldn't believe that anyone would build anything at all in this wilderness.
BBC - WW2 People's War - Memoirs of a Jock 39/45