Complex sentence: Vilnius Metro (Lithuanian: "Vilniaus metropolitenas")--is a planned rapid transit system in the Lithuanian capital Vilnius, 3 lines are currently proposed to connect the busiest and most populous city districts.
Split into simpler sentences: Vilnius Metro (Lithuanian: "Vilniaus metropolitenas")--is a planned rapid transit system in the Lithuanian capital Vilnius. Three lines are currently proposed to connect the busiest and most populous city districts.