The most striking physical features of Bhutan is its architecture. The characteristic style and color of every building and house in the kingdom is a distinct source of aesthetic pleasure. The dzongs - themselves imposing 17th century structures built on a grand scale without the help of any drawings and constructed entirely without nails - are outstanding examples of the best in Bhutanese architecture. Patterns of rich colors adorn walls, beams, pillars and doors in traditional splendor. As with its architecture, art and painting are important aspects of Bhutanese culture and they bear testimony to the spiritual depth of Bhutanese life.