Create a vibrant, visually captivating poster that features an urban cityscape constructed entirely out of colorful, oversized building blocks. The blocks form iconic landmarks and skyscrapers, with whimsical details like windows and doors painted on. In the foreground, diverse people of all ages and backgrounds are interacting with the blocks, building and rearranging them as if the city is a giant, collaborative playground. The sky above is full of floating block clouds and a radiant sun made of interlocking pieces. Bold, playful typography at the top of the poster reads "Build Your Dream City - Discover the Power of Creativity!"