Prompt: Write a short story about a man who discovers a magical portal

John was walking down the street when he saw a large, green portal in the middle of the road. He knew that he had to explore it. He stepped through and found himself in a world of magical creatures. He saw a dragon flying overhead, a unicorn grazing in the meadow, and a beautiful girl dancing in the forest. John was amazed by the beauty of the world and decided to stay for a while.