Complex sentence: Largo Town Center, along with Morgan Boulevard, marks the first extension of Metro beyond the official original adopted regional system, but in a 1970 WMATA reginoal phase map, Largo Town Center, simply called Largo, was part of the system.
Split into simpler sentences: Largo Town Center, along with Morgan Boulevard, marks the first extension of Metro beyond the official original adopted regional system. However, in a 1970 WMATA regional phase map, Largo Town Center, simply called Largo, was part of the system.