The arch was built between 211 and 214 by means of a testamentary donation of Gaius Cornelius Egrilianus, Prefect of the XIV legion, who was originally from Thebeste. The figure set aside for the construction was 250,000 sesterti.
Later, the arch was reused as the northern gate of the city wall in the Byzantine period. The lateral arches were walled up, as was the northern one, until they were reopened by French military engineers during the colonial period.
In form it is roughly cubical, being 10.94m on the side and to the top of the entablature. On the pylons, beside the spans are pairs of columns with Corinthian capitals, detached from the wall and with pilasters behind, supported by a podium from which their pedestals extend. The main entablature is above the pairs of columns and continues in the recess above the spans. Medallions with the busts of divinities are located above each of the spans.
On the attic on three sides dedications are inscribed to the deified Emperor Septimius Severus, Julia Domna and Caracalla. On the fourth side is a reconstructed Byzantine inscription, originally found in the infill of the vaults, which refers to the incorporation of the arch into the Byzantine city wall as the work of the magister militum Solomon.
At the centre on all sides, the entablature supported an aedicula which held a statue.
The reconstruction of the very top of the arch is the subject of some debate among scholars: According to Meunier an octagonal lantern would have stood there with its base hidden by the aediculae, while according to another there would have been a low dome. According to Bacchielli, the four aediculae, connected by railings contained the statues of the Deified Septimius Severus, the Deified Julia Domna, Caracalla and Geta.References:
The famous Italian Medici family have given two queens to France: Catherine, the spouse of Henry II, and Marie, widow of Henry IV, who built the current Luxembourg palace. Maria di Medici had never been happy at the Louvre, still semi-medieval, where the fickle king, did not hesitate to receive his mistresses. The death of Henry IV, assassinated in 1610, left the way open for Marie's project. When she became regent, she was able to give special attention to the construction of an imposing modern residence that would be reminiscent of the Palazzo Pitti and the Boboli Gardens in Florence, where she grew up. The development of the 25-hectare park, which was to serve as a jewel-case for the palace, began immediately.
The architect, Salomon de Brosse, began the work in 1615. Only 16 years later was the palace was completed. Palace of Luxembourg affords a transition between the Renaissance and the Classical period.
In 1750, the Director of the King's Buildings installed in the wing the first public art-gallery in France, in which French and foreign canvases of the royal collections are shown. The Count of Provence and future Louis XVIII, who was living in Petit Luxembourg, had this gallery closed in 1780: leaving to emigrate, he fled from the palace in June 1791.
During the French Revolution the palace was first abandoned and then moved as a national prison. After that it was the seat of the French Directory, and in 1799, the home of the Sénat conservateur and the first residence of Napoleon Bonaparte, as First Consul of the French Republic. The old apartments of Maria di Medici were altered. The floor, which the 80 senators only occupied in 1804, was built in the middle of the present Conference Hall.
Beginning in 1835 the architect Alphonse de Gisors added a new garden wing parallel to the old corps de logis, replicating the look of the original 17th-century facade so precisely that it is difficult to distinguish at first glance the old from the new. The new senate chamber was located in what would have been the courtyard area in-between.
The new wing included a library (bibliothèque) with a cycle of paintings (1845–1847) by Eugène Delacroix. In the 1850s, at the request of Emperor Napoleon III, Gisors created the highly decorated Salle des Conférences, which influenced the nature of subsequent official interiors of the Second Empire, including those of the Palais Garnier.
During the German occupation of Paris (1940–1944), Hermann Göring took over the palace as the headquarters of the Luftwaffe in France, taking for himself a sumptuous suite of rooms to accommodate his visits to the French capital. Since 1958 the Luxembourg palace has been the seat of the French Senate of the Fifth Republic.