The architectural traditions of Bangladesh have a 2,500-year-old heritage. Terracotta architecture is a distinct feature of Bengal. Pre-Islamic Bengali architecture reached its pinnacle in the Pala Empire, when the Pala School of Sculptural Art established grand structures such as the Somapura Mahavihara. Islamic architecture began developing under the Bengal Sultanate, when local terracotta styles influenced medieval mosque construction. The Adina Mosque of United Bengal was the largest mosque built on the Indian subcontinent.