One of the most striking physical features of Bhutan is its architecture. Bhutanese architectural forms comprise chortens (stupas) stone walls, temples/monasteries, fortresses, mansions, and houses. The characteristic style and colour of every building and house in the kingdom is a distinct source of aesthetic pleasure. What makes the Bhutanese architectural landscape unique is the consistency of traditional designs found in both old and new structures. Thus the ancient fortresses and temples seem to merge with the modern-day structures thereby creating a consistency in the architectural landscape. 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 colours adorn walls, beams, pillars, and doors in traditional splendor.