Some of the finest ancient ruins of the Roman world are found in Libya. Leptis Magna has gained its reputation from never having had any adjacent succeeding cities; nobody needed to reuse its stones for new building projects. What makes Leptis great is not all in all individual structures, but the extent of the site. You can almost get a grasp on what the place looked like.
The most famous single Roman structure of Libya is however, at Sabratha, with its fabulous theatre. Although rebuilt, it is one of the finest theatres you can visit anywhere.
Out from Leptis, the wealthy mansion known as Villa Sileen is a gem.
Libya's capital, Tripoli, is built over an ancient city, but right there in the middle of the centre, remains of an ancient past are still standing.
Cyrene in the east of Libya is by far the best Greek ruin city in North Africa. Contrary to what many are aware, Greek cities in this part of the world were converted into Roman cities. Cyrene is among the finest that show a true Greek city; there are Roman remains here as well. To Cyrene, there were two ports. Apollonia has survived fairly well, but little of it show Greek remains, rather it exhibits Byzantine structures, then mainly churches. The other port, Ras al-Hillal has little to show now, although some remains of a church is quite interesting.
Within short distance, check out the two churches at L'Atrun, as well as the mosaics of Qasr Libya.
There are a few ancient sites in Libya showing indigenous culture. This culture is everything but isolated, employing architectural elements found as far east as Syria and Iraq. Ghirza was on the border to the Roman empire, while Germa was the capital of an empire ruling far south when Sahara was greener than today. Slonta in the east, is very limited, but strange and fascinating, with its human figures carved out by a true artist in a lost past.