What's the must-see thing in Split?

Diocletian's Palace covers roughly 30,000 square metres of central Split. The emperor abdicated in 305 AD and moved here to grow cabbages. That is not a metaphor. The walls still stand 15 to 26 metres high in places. Enter through the Bronze Gate on the Riva and you step from bright Adriatic sun into the basement halls, where the air drops 5 or 6 degrees and smells like wet limestone. These vaulted corridors held up the palace floors for 1,700 years before archaeologists cleared them in the mid-20th century. Walk north to the Peristyle, the open courtyard at the center of the complex. Pink-veined marble columns have held this space open since the 4th century, and the acoustics bounce conversation off the stone in a way that makes 20 people sound like 200. At 8am in August, you might have the Peristyle nearly to yourself. By noon on a day like today, 32°C with 31% humidity, the flagstones radiate heat and cruise-ship tours fill the courtyard three-deep.

The Cathedral of Saint Domnius sits on the east side of the Peristyle. It began as Diocletian's mausoleum, which likely makes it the oldest cathedral structure still serving its original liturgical purpose anywhere. The irony is hard to miss. Diocletian persecuted Christians more aggressively than any Roman emperor before him, and they turned his tomb into their church. The bell tower costs about €5 and the 183 steps up a narrow medieval staircase deliver a 360-degree view over Split's terracotta rooftops, the harbour, and the islands of Brač and Hvar in the distance. The stairs are uneven, worn smooth by centuries of feet, with no railing in some sections. Worth it. Across the Peristyle, the Temple of Jupiter still stands in its original Roman proportions. It has served as a baptistery since the early Middle Ages. The carved stone barrel vault overhead carries relief work from Diocletian's era, and the whole visit takes 10 minutes.

Marjan is the forested hill on Split's western peninsula, and it is the thing most first-time visitors skip because it does not feel 'historic' in the palace sense. That is a mistake. The 178-metre summit sits 20 minutes on foot from the Riva, and the trail climbs through Aleppo pine forest where cicadas are so loud in summer they drown out conversation. The air shifts from stone-and-coffee to pine resin within the first 100 metres of the climb. At the top, the view west toward Čiovo island and the open Adriatic is the best free vantage point in the city. Bring water. There is no shade on the final approach, and on an August afternoon the heat differential between the pine canopy and the exposed summit is stark. The small 13th-century Church of St. Nicholas near the summit path tends to be locked, but the stone terrace beside it is the spot.

Split's cruise traffic peaks between 10am and 4pm from June through September, and the palace's narrow Roman-era alleys squeeze everyone into single-file traffic. The best first-day sequence is the palace at opening, the bell tower by 9am, then the walk to Marjan while groups are still queuing at the Golden Gate for guided tours. Skip Salona on your first day. The ancient Roman capital 5 kilometres northeast in Solin covers a large open site with almost no shade, and it needs a bus ride and at least two hours to do properly. Save it for a morning on day two or three. Close your first day on the Riva promenade around 7pm, when Split's residents take their evening korzo walk. The smell of grilled fish drifts from Matejuška harbour, cold Ožujsko at one of the waterfront cafés. The korzo tends to wind down by 10pm.