Zadar
The Sea Organ was built according to the design of the Zadar architect Nikola Bašić. It is situated near the new cruiser quay on the Zadar waterfront. It is easily recognisable as a differently shaped part of the seafront consisting of steps leading down to the sea. The stone steps extend for about 70 metres along the seafront. Underneath, at the level of the lowest tide, there are 35 pipes of different lengths and diameters, which are tilted at different angles. These are built vertically in relation to the seafront and rise aslant up to the paved part of the waterfront, ending up in a channel (service corridor). On the pipes, there are whistles which can play 7 chords and 5 tones. Above the channel, there are perforated stone steps through which the sound comes out, the air pushed by the sea.
Source: http://www.zadar.hr/