This article: Palmyra began as a small settlement near the Efqa spring on the southern bank of Wadi al-Qubur. The settlement, known as the Hellenistic settlement, had residences expanding to the wadi's northern bank during the first century. Although the city's walls originally enclosed an extensive area on both banks of the wadi, the walls rebuilt during Aurelian's reign surrounded only the northern-bank section. Most of the city's monumental projects were built on the wadi's northern bank, among them is the Temple of Bel, on a tell which was the site of an earlier temple (known as the Hellenistic temple). However, excavation supports the theory that the tell was originally located on the southern bank, and the wadi was diverted south of the tell to incorporate the temple into Palmyra's late first and early second century urban organization on the north bank.Also north of the wadi was the Great Colonnade, Palmyra's 1.1-kilometre-long (0.68 mi) main street, which extended from the Temple of Bel in the east, to the Funerary Temple no.86 in the city's western part. It had a monumental arch in its eastern section, and a tetrapylon stands in the center. The Baths of Diocletian, built on the ruins of an earlier building which might have been the royal palace, were on the left side of the colonnade. Nearby were residences, the Temple of Baalshamin, and the Byzantine churches, which include "Basilica IV", Palmyra's largest church. The church is dated to the Justinian age, its columns are estimated to be 7 metres (23 ft) high, and its base measured 27.5 by 47.5 metres (90 by 156 ft).The Temple of Nabu and the Roman theater were built on the colonnade's southern side. Behind the theater were a small senate building and the large Agora, with the remains of a triclinium (banquet room) and the Tariff Court. A cross street at the western end of the colonnade leads to the Camp of Diocletian, built by Sosianus Hierocles (the Roman governor of Syria). Nearby are the Temple of Al-lat and the Damascus Gate. contains an answer for the question: What had a monumental arch in its eastern section, and a tetraylon stands in the center?, what is it ?
Answer:
the Great Colonnade