A listing of known architectural feats during the reign  of Severus Alexander.  If you find one I don't have, please email me a picture.

The Arch of Severus Alexander at Dougga, Tunisia

Dougga, one of the most important sites of the country has a Libyco-Punic mausoleum, a capitol, a theater, thermal baths, monumental arches, temples and extremely well preserved houses.
Of Numidian origin, Dougga is representative of the Romano-Africa civilizations, an original and brilliant civilization which witnessed the birth of numerous cities and developed its own architectural style as well as the flourishing art of mosaics. Dougga is located 100 km west of Tunis, 7 km south of Teboursouk.

The Roman ruins are spread out across a plateau and on to the steep side of the djebel overlooking the Cued Khaled. It was originally a Numidian town allied with Rome against Carthage. As a consequence, after the downfall of Carthage, the town was granted a certain degree of independence. Romanization only started towards 150 AD, after two centuries of coexistence. By the time Carthage had been rebuilt by the Romans, Dougga had become the economic and administrative centre of a very rich agricultural area. It also controlled the route to the coast, and enjoyed great prosperity. Having become a Roman colony by the end of the second century, the town reached the height of its wealth under the rule of Septimius Severus. Its downfall in the fourth century was caused by the heavy duties paid to the Romans and religious quarrels. When the Vandals invaded, most of the population had moved to Teboursouk

Pictures from different angles of the arch.

Next two pictures used with permission of Dickson Archive.