Visitors watch the "big ben" and "tower bridge" made by colorful tulips in the famous Keukenhof park in Lisse, the Netherlands, on May 3, 2013. (Xinhua/Robin Utrecht)

Visitors watch the "big ben" and "tower bridge" made by colorful tulips in the famous Keukenhof park in Lisse, the Netherlands, on May 3, 2013. (Xinhua/Robin Utrecht)