The St. Augustine Historic District is located in St. Augustine, Florida, and is known for being the oldest continuously inhabited European-established settlement in the continental United States. This area features cobblestone streets, historic buildings, and landmarks that reflect Spanish colonial architecture, including the famous Castillo de San Marcos, a 17th-century fortress. Visitors can explore numerous attractions, such as the Lightner Museum, which showcases 19th-century art and artifacts, and the Flagler College, originally built as a hotel by industrialist Henry Flagler. The district offers a glimpse into the rich history and cultural heritage of this unique city.