Riyadh Metro inaugurated three of its six lines on Sunday, a milestone for the city’s infrastructure which provides residents and visitors with a long-anticipated public transit option in an otherwise car-dependent city suffering worsening gridlock.

Riyadh's new unmanned metro service, partly designed and built by Samsung C&T, began operations on Sunday. The network includes six lines and spans a total of 176 kilometers of track. The Korean construction giant described the project as "the largest of its kind in the world.