Throughout Zoroastrian history, shrines and temples have been the focus of worship and pilgrimage for adherents of the religion. Early Zoroastrians were recorded as worshiping in the 5th century BCE on mounds and hills where fires were lit below the open skies. In the wake of Achaemenid expansion, shrines were constructed throughout the empire and particularly influenced the role of Mithra, Aredvi Sura Anahita, Verethragna and Tishtrya, alongside other traditional Yazata who all have hymns within the Avesta and also local deities and culture-heroes. Today, enclosed and covered fire temples tend to be the focus of community worship where fires of varying grades are maintained by the clergy assigned to the temples.