What Roman city in Libya, birthplace of Septimius Severus, has extensive ruins?

The Roman city in Libya, birthplace of Septimius Severus and known for its extensive ruins, is Leptis Magna.

Originally a Punic settlement near the mouth of the Wadi Lebda, Leptis Magna became an important Roman port and trading center. Its greatest building boom began after Septimius Severus became emperor in 193 AD. Proud of his hometown, he funded monumental projects including a new forum, basilica, harbor improvements, and a triumphal arch.

The city prospered through Mediterranean and trans-Saharan trade, handling goods such as ivory, gold, ebony, ostrich feathers, and wild animals. At its height in the early third century, it may have had roughly 100,000 inhabitants. Its surviving remains include broad streets, markets, baths, theaters, temples, arches, and richly decorated civic buildings.

Leptis Magna declined after Vandal conquest, later Byzantine rule, raids, and the disruption of trade. Abandonment allowed sand to cover and protect much of the site. It was excavated extensively during the twentieth century and was inscribed as a UNESCO World Heritage Site in 1982.