hold around 50,000 spectators. Another iconic Roman structure that demonstrates their precision and technological advancement is the Pont du Gard in southern France, the highest surviving Roman aqueduct. Americas (Pre-Columbian) From over 3,000 years before the Europeans 'discovered' America, complex societies had already been established across North, Central and South America. The most complex ones were in Mesoamerica, notably the Mayans, the Olmecs and the Aztecs, but also Incas in South America. Although knowledge of astronomy and engineering was limited, structures and buildings were often aligned with astronomical features or with the cardinal directions. Much of the architecture developed through cultural exchange – for example the Aztecs learnt much from earlier Mayan architecture. Many cultures built entire cities, with monolithic temples and pyramids decoratively carved with animals, gods and kings. Most of these cities had a central plaza with governmental buildings and temples, plus public ball courts, or tlachtli, on raised platforms. Just like in ancient Egypt, here were built pyramids too, being generally stepped. They were probably not used as burial chambers, but had important religious sites at the top. They had few rooms, as interiors mattered less than the ritual presence of these imposing structures and the public ceremonies they hosted; so, platforms, altars, processional stairs, statuary, and carving were all important. South Asia After the fall of the Indus Valley, South Asian architecture entered the Dharmic period which saw the development of Ancient Indian architectural styles which further developed into various unique forms in the Middle Ages, along with the combination of Islamic styles, and later, other global traditions. Ancient Buddhist Buddhist architecture developed in the Indian subcontinent during the 4th and 2nd century BC, and spread first to China and then further across Asia. Three types of structures are associated with the religious architecture of early Buddhism: monasteries (viharas), places to venerate relics (stupas), and shrines or prayer halls (chaityas, also called chaitya grihas), which later came to be called temples in some places. The most iconic Buddhist type of building is the stupa, which consists of a domed structure containing relics, used as a place of meditation to commemorate Buddha. The dome symbolised the infinite space of the sky. Buddhism had a significant influence on Sri Lankan architecture after its introduction, and ancient Sri Lankan architecture was mainly religious, with over 25 styles of Buddhist monasteries. Monasteries were designed using the Manjusri Vasthu Vidya Sastra,