“Castles in the Sky” is the debut single by Belgian Eurodance project Ian Van Dahl, founded by music producers Christophe Chantzis and Erik Vanspauwen. Marsha (full name Martine Theeuwen) was recruited as vocalist, but Cindy Mertens (and later Annemie Coenen) was hired as the onstage frontwoman, miming to Marsha’s vocals.

Whilst a modest chart success across Europe in 2000, the song became a huge hit in the UK when it was released there the following year. It peaked at number 3 and has been certified Gold for sales of over 400,000 copies.