<P> The site is roughly divided into an urban sector and an agricultural sector, and into an upper town and a lower town . The temples are in the upper town, the warehouses in the lower . </P> <P> The architecture is adapted to the mountains . Approximately 200 buildings are arranged on wide parallel terraces around an east - west central square . The various compounds, called kanchas, are long and narrow in order to exploit the terrain . Sophisticated channeling systems provided irrigation for the fields . Stone stairways set in the walls allowed access to the different levels across the site . The eastern section of the city was probably residential . The western, separated by the square, was for religious and ceremonial purposes . This section contains the Torreón, the massive tower which may have been used as an observatory . </P> <P> Located in the first zone are the primary archaeological treasures: the Intihuatana, the Temple of the Sun and the Room of the Three Windows . These were dedicated to Inti, their sun god and greatest deity . </P> <P> The Popular District, or Residential District, is the place where the lower - class people lived . It includes storage buildings and simple houses . </P>

When was machu picchu discovered and by whom