Saint Domnius Cathedral, located in Split, Croatia, is a must-see historical site built within the ancient Diocletian's Palace. As one of the oldest Catholic cathedrals still in use, it offers a rich blend of Roman and Christian history. Accessibility might be challenging for those with mobility issues due to the old structure and steps. A solo visit is feasible and allows for independent exploration, but a guided tour can provide deeper historical context. The best time to visit is during the shoulder seasons (spring or fall) to avoid the summer crowds. Expect to spend around 1-2 hours exploring the cathedral and its bell tower. The approximate cost for entry is relatively low, typically a few euros, but climbing the bell tower may incur an additional fee. Be mindful of dress codes when entering religious sites.