The second-largest city in Croatia, Split, lies on the Adriatic Sea. The city is renowned for its ancient center that dates back to Roman times, and much of the architecture has been incorporated into newer buildings over time. As the city is very picturesque and unique, it has served as scenery for film and television, most notably "Game of Thrones," parts of which were filmed in Diocletian's Palace, dating back to the 4th century. St. Duje's Cathedral was originally Diocletian's mausoleum, making it the oldest cathedral in the world. The Campanile is situated right next to the cathedral, a bell tower built in Romanesque architecture. These are just a few of the city's ancient attractions. Of note is Krka National Park, about an hour from Split, which features a large natural pool with 17 waterfalls all feeding into it simultaneously.