Same as other reviewers here, what impressed me most was the very fact that an ancient Roman palace evolved into a city! This is amazing and creats a sense of unity and intimacy when visiting this unbelievable complex. There's even Jupiter's Temple still standing with its original Roman ceiling ornated with masks! You should definitey take your time to explore the palace (although I found one day enough for this purpose). Other nearby attractions are the archaeological museum with a beautiful garden protraying important Roman findings from the area (I would say the garden which is free of charge is more interesting to visit than the interior of the museum), the Mestrovic Gallery and Church (both certainly merit a visit) and the lovely beaches. Day trips are possible to Salona (the nearby Roman settlement) and Torgir - a WHS on its own right, both accessible by local buses.