Apparently many more Inca sites and trails can be found all over these parts, but there is a concentration around Cusco on the centre of the Empire. Cusco was the primary capital and this was where the Incan ceremonies and festivals were held, during which mummified Incan rulers or nobles that had transcended in the 'higher world' were carried in procession around the central square. The primary festivals were the summer and winter solstices that signified a time of change that the civilisation relied upon for farming, house building, and organising their society.
Incan society included scientists and astronomers that lived amongst the priests, nobles, and rulers, in citadels like Machu Picchu that were built high in the mountains as near to the 'higher world' as possible. The 'higher world' (represented by the highest flying bird in the world -the condor) referred to the gods, embodied by the stars that filled the night sky, and it was the appearance or location of certain constellations that provided more detailed guidance for the Incan calendar and subsequent actions in the 'middle world' which was inhabited by mortals. Human sacrifice was ritually practiced as well as (probably much later) sacrifice of Llamas or Alpacas. The sun was also worshipped as it was understood that it brought life to the earth, and many advanced scientific and architectural techniques were used to build sundials and temples (like those atop Machu Picchu) in which shadows were cast with great accuracy to provide the Incan rulers with significant knowledge about their place in the world and consequently hold great power over the common people.