Probably because of its strategic position this fortress was used as an excellent observation point to watch for the enemies of the North. Also Rumicucho is known for being an astronomic observatory. Based in the investigations of the archaeologist Eduardo Almeida who studied the ruins for 25 years, he discovered that the most important place in Rumicucho were not the terraces but two oval room and a rock; and it is believed that this were built strategically to represent the equinoxes and solstices.
In Rumicucho you have a great view of the Cayambe and La Marca mountains, which form a horizontal line going from East to West and were the sun goes through during the equinox. This is why it is believed that Pucara de Rumicucho was also a place of worship to the sun. If these theory are true we can say that the civilizations before the Spanish and Incas were very advanced in their astronomic knowledge.