Eager to establish his own legitimacy, Zhu Di voided the Jianwen Emperor's reign and established a wide-ranging effort to destroy or falsify records concerning his childhood and rebellion. This included a massive purge of the Confucian scholars in Nanjing and grants of extraordinary extralegal authority to the eunuch secret police. One favorite was Zheng He, who employed his authority to launch major voyages of exploration into the South Pacific and Indian Oceans. The difficulties in Nanjing also led the Yongle Emperor to re-establish Beiping (present-day Beijing) as the new imperial capital. He repaired and reopened the Grand Canal and, between 1406 and 1420, directed the construction of the Forbidden City. He was also responsible for the Porcelain Tower of Nanjing, considered one of the wonders of the world before its destruction by the Taiping rebels in 1856. As part of his continuing attempt to control the Confucian scholar-bureaucrats, the Yongle Emperor also greatly expanded the imperial examination system in place of his father's use of personal recommendation and appointment. These scholars completed the monumental "Yongle Encyclopedia" during his reign.