Kyoto's most famous and enduring nickname is "The City of Ten Thousand Temples." This refers to the incredible density of historical and religious sites within the city, which served as Japan's imperial capital for over 1,000 years. It is also frequently called the "Cultural Capital of Japan" or the "Heart of Japan" because it preserved much of its traditional wooden architecture and "Old World" atmosphere while other cities like Tokyo were modernized or destroyed during World War II. Historically, the city was known as Heian-kyo, meaning "The Capital of Peace and Tranquility." Today, it is also synonymous with Gion, the famous Geisha district. Because of its deep roots in Japanese history, Kyoto is seen as the guardian of traditional arts, including the tea ceremony, kaiseki dining, and kimono weaving, making it the most important destination for those seeking the "authentic" soul of Japanese culture.