Travel to Zadar, the oldest continuously inhabited city in Croatia, and enjoy a walking tour with a local guide on arrival. Visit the 9th-century St Donatus Church, one of the only buildings from this period to survive the Mongol invasion. Later in the afternoon you'll head to the unique Sea Organ, which generates music via sea waves, using tubes placed beneath a set of broad marble stairs. It's not only a profound piece of art, highlighting the long history of the town, but also a feat of engineering. As darkness falls, enjoy a glass of sparkling wine at nearby Monument to the Sun, an in-ground monument consisting of 300 multi-layered glass plates in a 22-metre (72 foot) diameter circle that produces a stunning show of light after dark. It works in tandem with the Sea Organ -- one communicates with light, the other with sound. (B/L)