Roman rule denied Herod the chance to expand his power by military means; the money he saved
through not building up armies and going to war was invested in great buildings in Jerusalem, Caesarea Maritima and other locations in Palestine. The most significant of these projects was the construction of the Herodian temple in Jerusalem, including the expansion of the temple plateau.
Herod was an absolute monarch. He was bound to Rome as a client king in foreign policy terms, but within his kingdom he had absolute power. His historical image is initially based on the positive depiction of him as an active ruler by Nikolaos of Damascus, whose writings are partly preserved as copies in Josephus’ account of The Jewish War. (Bell. 1, 31-2, 116).
When the situation in Rome changed and Emperor Nero appeared as a tyrant, Herod was also presented as a tyrant by Josephus (Antiquities of the Jews) and in Matt. 2.