Design a captivating Facebook post illustration that promotes cheap air tickets for tourists. The background should consist of a vibrant collage of iconic landmarks, including the Sydney Opera House, Big Ben, and the Taj Mahal, creating a sense of adventure and exploration. Utilize a bright and vibrant color palette with shades of blue, green, yellow, and red to evoke excitement and positivity. In the center, feature the text "Cheap air ticket Guaranteed" in a bold and modern typeface, ensuring it is easily readable against the colorful backdrop, possibly using a white or light-colored font with a subtle shadow for contrast. Below the text, add a prominent CTA button labeled "Call Now," styled in a contrasting color like bright red or green to draw attention. Incorporate playful airplane icons throughout the design, adding a dynamic element that reinforces the travel theme while ensuring they do not clutter the composition. The overall composition should be visually striking and professional, perfect for engaging potential customers on Facebook.