The term SEAT OF AN EMPIRE can be solved by the crossword solution OTTOMAN, which is a seven-letter word. The OTTOMAN EMPIRE was a major power in the Middle East and Eastern Europe from the 14th to the early 20th century. It was founded by the Turkish tribal leader Osman I in 1299 and lasted until its dissolution in 1922. The OTTOMAN EMPIRE was known for its military strength, its vast cultural and religious diversity, and its influence on the development of modern Europe. The capital of the OTTOMAN EMPIRE was Istanbul, which was also the SEAT of the EMPIRE.