 Other examples of Song bridges include Guyue Bridge , a stone arch bridge in Yiwu , Zhejiang Province . The bridge was built in 1213 , the sixth year of the Jiading Era in the Southern Song dynasty . Song @-@ era pontoon bridges include the Dongjin Bridge , 400 m ( 1 ⁄ 4 mi ) long , which may still be seen today . 
