Create an image depicting a mystical and ancient city floating in the clouds of a vibrant and colorful sky, showcasing a fusion of old world architecture and futuristic elements.

Illustrate a fantasy scene revealing a mystical and ancient city that levitates in the billowing clouds. The sky is alive with an array of vibrant colors, from the warm hues of a setting sun to the deep blues of the midday. The city architecture is a harmonious blend of old-world structures, exhibiting features like domed rooftops, carved balustrades, and intricate masonry, combined ingeniously with elements of a futuristic tableau such as sleek metal beams, glowing neon lights, and high-tech transportation methods. The overall effect is a paradoxical balance of past and future, tradition and innovation, contributing to the city's enigmatic charm.