Double-decker buses are large vehicles designed to carry passengers on two levels. They are commonly found in cities like London, where they are an iconic part of public transportation. The upper deck offers a unique view of the surroundings, making them popular among tourists and locals alike. These buses typically have a staircase leading to the second level and can accommodate more passengers than single-decker buses. They are often painted in bright colors and feature large windows, enhancing the travel experience. Many cities around the world use double-decker buses to improve efficiency in public transit systems.