The Council of Nicaea (325 AD) declared that the Christian Easter would be celebrated on the Sunday following the first full moon of spring. Spring begins between the 20th and the 21st of March, coinciding with the astronomical Equinox. Thus, in Guatemala, two festivities of two different cultures and spiritualties are celebrated at the same time. In the ritual centres of ancient Mayan cities, indigenous people celebrate the Equinox annually on the 21st of March to herald the rising of the sun and the beginning of a new period of fertility. A few days later, Christian Holy Week takes place, celebrated mainly in urban centres and especially in the city of Antigua, the former colonial capital. During Holy Week, Christians commemorate the last days of Jesus.