The period of the imperial Cholas (c. 850 CE - 1250 CE) in South India was an age of continuous improvement and refinement of Chola art and architecture. They utilised the wealth earned through their extensive conquests in building long-lasting stone temples and exquisite bronze sculptures, in an almost exclusively Hindu cultural setting. The Cholas built their temples in the traditional way of the Pallava dynasty, who were themselves influenced by the Amaravati school of architecture. The Chola artists and artisans further drew their influences from other contemporary art and architectural schools and elevated the Chola temple design to greater heights. The Chola kings built numerous temples throughout their kingdom, which normally comprised the plains, Central and Northern Tamil Nadu and at times the entire state of Tamil Nadu as also adjoining parts of modern Karnataka and Andhra Pradesh. In the evolution of the Chola temple architecture we can roughly see three major phases, beginning with the early phase, starting with Vijayalaya Chola and continuing till Sundara Chola, the middle phase of Rajaraja Chola and Rajendra Chola when the achievements scaled heights never reached before or since and the final phase during the Chalukya Chola period of Kulottunga I till the demise of the Chola empire. The Cholas in addition to their temples, also built many buildings such as hospitals, public utility buildings and palaces. Many such buildings find mention in their inscriptions and in contemporary accounts. The golden palace that Aditya Karikala supposedly built for his father Sundara Chola is an example of such a building. However, such buildings were of perishable materials such as timber and fired bricks and have not survived the ravages of time. Early Chola Period Pallavas were the first recognisable South Indian dynasty who indulged in the pursuit of architectural innovations. The first seeds of Chola temple architecture in Tamil Nadu were possibly sown during this period. The temple architecture evolved from the early cave temples and monolith temples of Mamallapuram to the Kailasanatha and Vaikuntaperumal temples of Kanchipuram. This architecture style formed the foundation from which the Cholas, who were in close contact with the Pallavas during their periods of decline, took some valuable lessons according to Nilakanta Sastri, in his A History of South India. The early Cholas built numerous temples. Aditya I and Parantaka I were prolific builders for their faith. Inscriptions of Aditya I record that he built a number