Rising above the concrete slopes of Cincinnati`s Public Landing is a three-story, 60 ton, exact replica of the original red paddle wheel from the American Queen riverboat. It is positioned about 40 feet off the ground, above a series of 24 metal smokestacks in what is known as the Dan and Susan Pfau Whistle Grove. The smokestacks showcase the importance of steam in the early days of riverboat travel and the relevance that riverboats played in the early history of Cincinnati. Visitors to the Whistle Grove are able to control the steam released from each of the stainless steel smokestacks by simply walking by several computer synchronized motion sensors installed in each column. Different sounds will be triggered by passing by the various columns, including calliope music, a steamboat whistle and voices of river veterans talking about the rigors of life on the Ohio. All of the columns emit steam, generated by boilers in a nearby steam room. At the center of the Whistle Grove is a riddle that, once solved, touches off an especially unique, interactive steam display. When all smokestacks shoot steam at once, a misty cloud envelopes the paddle wheel, creating a surreal scene and as picturesque a photo opportunity as there is in town. The Riddle: In order to make this grove sing – You`ll walk an X within the ring Start here – and move towards the tide Circle close ‘round the last stack, - Turn back in stride. Now walk towards the city – And turn as before To the center, turn left – And repeat it once more. Stand still – Listen and chill Watch the rhythmatic steam The hidden music is in between.