Running southward from Xuande Gate was the Imperial Boulevard , about two hundred paces wide , with the Imperial Corridors on either side . Merchants opened shops in the Corridors until 1112 , when they was banned . Two rows of black fencing was placed at the center of the boulevard as a barrier to pedestrians and carriages . Along the inner sides of the fences ran the brick @-@ lined Imperial Water Furrows , filled with lotus . About 400 m ( 1 @,@ 300 ft ) south from Xuande Gate , the Bian River intercepted the Imperial Boulevard , which crossed it over the stone Zhou Bridge , balustraded and flat @-@ decked . This design of a boulevard with a stone bridge crossing a river was later imitated in the Forbidden City . During spring and summer , mingled peach , plum , pear and apricot trees adorned the banks of the Bian with a variety of flowers .