It may be hard to tear yourself away from the Croatian islands and coast but a trip inland to Mostar is highly recommended. The most famous Mostar sight is the Old Bridge, built in 1556 and then, famously, blown up in 1993 during the last Balkan war. The bridge has been reconstructed and is as beautiful as ever, spanning the azur Neretva river with a mountainous backdrop.
The bridge has tremendous symbolic value as it links the Croat and Muslim communities each located on opposite sides of the river. Its destruction and reconstruction comprise one of the rare happy endings in the Balkans.
I started out from Split in mid-morning, taking the incompleted motorway south from Split until it ended somewhere after Sestanovic. I then followed Rt 62 which took me across the border at Metkovic. From there, it was just a matter of following the Neretva river north to Mostar. The ride was somewhat longer than I had expected, taking nearly 4 hours, largely because the road was unfamiliar. Still the trip was a little too long to be a viable day trip from Split.
Upon entering the perimeter of the Old Town, I was diverted by police away from the center. It turned out that a football match that evening was to involve opposing Muslim and Croat teams and police were preparing for possible violence (that fortunately never happened).
I checked into the wonderful Hotel Kriva Cuptija 2 (excellent value for money) and set out to explore the Old Town. On the way, the vestiges of the 1990s war were apparent in a number of buildings with pockmarked sides and blasted-out windows. The ancient cobblestoned streets on either side of the river were restored and bustling with life. The differences between the Croat and Muslim side were subtle: a few churches on one side; a few more mosques and cafes on the other. Everywhere the atmosphere was relaxed and friendly; people chatted easily with each other and with an inquisitive foreigner. The vivacious young woman at the hotel reception exuded hope and optimism for the future, assuring me that the days of ethnic hostilities were ancient history to the younger generation.
The following day I left for Dubrovnik and the trip was a very leisurely three hours, making Mostar a fascinating and easily doable day trip from Dubrovnik. Note that you will need to show your passport upon crossing the border as well as your auto insurance papers.