Paris is known as the world's most romantic city, with magical views of the city from the Seine at night and romantic places like Montmartre and the Champs-Elysees. Other romantic European cities mentioned include Venice, known for its canals, bridges and Piazza San Marco; Vienna, with its imperial palaces and forests; and Prague, with its historic bridges, squares and astronomical clock. The document also discusses romantic destinations in Bali, Barcelona, Cartagena, New York City, Rome, and San Francisco.