Originally, pergolas were climbing aids, for example, for vines, and did not shade the seating area over a wide area. Therefore, they can be supplemented with a slatted roof, blinds or an awning to provide shade. Today, pergolas are mainly made of aluminum, wood, metal or stone, as an extension or freestanding, and are open on the sides. Alternatives to the freestanding pergola include the gazebo, a hybrid of a garden shed and pergola, and the pavilion, usually a dome on columns. Other shade options include freestanding marquees or sun sails.