Initially the Buddha was worshiped in the form of specific symbols. The most prevalent symbol was the leaf of peepal (Ficus religiosa). Another symbol in use was the elephant. In course of time the sites containing these symbols were encircled with wood or stones. Thus gradually the Buddhist architecture took shape. The first such veneration sites are now lost. But we come across specimens of Buddhist religious monuments which belong to the third century B.C. onwards.

Types of Buddhist Architecture

The ancient Buddhist architectural types may be categorized as hereunder:-

1. Stupas – This category forms the most important class of buildings. A Stupa consists of detached pillars, towers, and tumuli, all of a sacred or monumental character. The word is a corrupted form of the Sanskrit word stupa, meaning a mound, heap or cairn.
2. Temples – Known as Chaitya halls, or caves.
3. Monasteries – Viharas, being the residences of the priests.

Buddhist Monasteries and Churches and the ruins of these works are among the oldest specimens of Indian architecture to be seen in the present day. Most of them were excavated in rocks, and not built up by laying stone upon stone. There are Chaityas or churches excavated in the Western Ghats which date from the third and second century before Christ; but the finest specimen of this kind of architecture is the church at Karli, half-way between Bombay and Poona, excavated in the first century before Christ.

Stupas

Besides churches and monasteries, the Buddhists raised Stupas or mounds on sacred spots, and these mounds were often surrounded by rails which were elaborately sculptured. There is a Stupa at Sarnath, near Varanasi, and some Stupas between the Indus and the Jhelum are known as the Manikyala Stupas, but the most important Stupas that still exist are those of Sanchi in Central India. The great Stupa of Sanchi is surrounded by rails ornamented with gateways which are finely sculptured. There were other older Stupas which have disappeared, but the surrounding rails still exist, as at Buddha Gaya and Bharahut, and the sculptures on these rails are among the oldest specimens of Hindu sculpture.

Temples

The history of ancient Indian architecture begins with Buddhist temples and cave temples. The oldest example of such class of monuments is the Bodh Gaya aka Mahabodhi temple. It is built in the Nagar style. The Emperor Ashoka is said to be the founder of Mahabodhi temple. With the propagation of Buddhism in other countries Buddhist temple architecture got a  great boost. In fact such temples are spread in a vast area beginning from Mongolia in the north to Sri Lanka in the south, and from Pakistan in the west to Vietnam in the east.  Some important temples related to Buddhism are:-

1. Kittisirimegha of Sri Lanka
2. Temple of the Tooth of Sri Lanka
3. Nippon temple of Japan
4. Wat Arun of Bankok
5. Candi Borobudur of Central Java
6. Adashino Nembutsu-ji of Japan
7. Big Bell Temple (Juesheng Temple) of China
8. Gandantegchinlen of Mongolia
9. Bongeunsa of South Korea

Viharas or monasteries

Among the Viharas or monasteries, still to be seen in India, some of the oldest are in the Udaygiri and Khandagiri hills in Odisha. There are small caves for single monks, as well as larger excavations with several rooms in them, all dating from some group of monasteries near Nasik in Western India; but perhaps the most interesting specimen are those of Ajanta, belonging to the fifth century after Christ. The walls are covered with fresco paintings which show the skill which the Hindus acquired in painting fifteen centuries ago.