The expansion of the Temple Mount platform and the erection of the Royal Stoa required Herod's engineers to overcome the difficult topographic conditions. It was thus necessary to build tall foundations above the slope of the Tyropoeon valley and equivalent tall foundations above the Kidron. The great effort invested in the construction of the Royal Stoa is a testimony of its immense importance to Herod and his status on the Temple Mount. Unlike his predecessors, the Hasmonean kings who had also served as High Priests, Herod was not of the priestly caste and was therefore unable to participate in priestly rituals. A client king appointed by the Romans, lacking legitimacy and unpopular with his subjects, Herod had initiated the Temple reconstruction to win favour among the Jews, but was forbidden from even entering the inner sanctum of his crowning achievement. It was thus the monumental Royal Stoa which gave Herod his rightful status on the Mount, a showcase of his majesty and grandeur.