Romans and Parthians
About 100 BC, the Hellenistic Greek kingdoms gave way to new conquerors. The Romans took over the West (modern Israel, Syria, Jordan, Armenia, and Turkey). The Parthians took over the East (modern Iraq, Iran, and Pakistan). The Romans built many Roman-style buildings all over their part of West Asia. They built amphitheaters and temples and paved roads and aqueducts.
Parthian architecture
The Parthians, because they had been nomads, did less building at first. But soon they also built roads and temples and palaces. The Arch of Sapor was part of the Sassanian kings’ palace. You went through this huge arch into the king’s throne room.
The Islamic Empire
Both the Romans and the Parthians ruled for hundreds of years. Then around 650 AD the Arabs conquered both empires. The Arabs reunited West Asia in the Islamic Empire. The Islamic caliphs built many beautiful mosques and palaces and other buildings. The Dome of the Rock in Jerusalem may be the most famous example. Islamic architecture soon dominated West Asia.
Islamic architecture
Bibliography and further reading about West Asian architecture:
The Art and Architecture of the Ancient Orient, by Henri Frankfort (5th edition 1997). The standard for college art history classes.
Persepolis: The archaeology of Parsa, seat of the Persian kings, by Donald Newton Wilber (1969).