Hollywood power couple Brad Pitt and Angelina Jolie are constructing anunderground theme park for their kids at their home in the south of France which will be powered bysun rays. ''Plans include a massive pool, slides, tunnels, boat rides, a pirate island with a castle, a go-kart track and even an old-fashioned carousel, a source told the National Enquirer magazine. ''Most ofthe park will be underground, with turf on top. It will be powered by sunlight, using panels in the roofand the water will be recycled.'' The couple raise six children together Maddox, 10, Pax, nine, Zahara,seven, Shiloh, five and three-year-old twins Knox and Vivienne.