The 400th anniversary of a significant event.

किसी महत्वपूर्ण घटना की 400वीं वर्षगांठ

English Usage: The town celebrated its quatercentenary with a grand festival.

Hindi Usage: नगर ने एक भव्य उत्सव के साथ अपनी 400वीं वर्षगांठ मनाई।