Not only did Jiufen's hilly terrain create many parallel roads at various altitudes, it also created the need for many tiny paths connecting these roads. This is the unique phenomenon of the "penetrant alley". A penetrant alley refers to "a narrow pathway found between houses or arcades". Based on this characteristic, we can categorize it in three groups: the first group consists of pathways sandwiched between two residential homes; the second group are the paths underneath residential houses, as if one is walking through an arcade or a mining tunnel; and the last group consists of steps between houses that connect two major roads.These penetrant alleys were a direct response to the large amount of immigrants during the heyday of the gold rush and the densely built housing communities such a sudden jump in population created. Residents wanted to maximize space for building new houses without sacrificing convenience and emergency escape routes; hence, these alleys formed as communities were built.A typical example of the first type of penetrant alleys is the "Dontiange Penetrant Alley"; it can be found between No.175 and No.177 Jishan St.; visitors can walk up the path to find the Dongtiange Cafe and the walls of Jiufen Elementary on LúnDǐng Rd. The entrance to the "Taro Potato Teahouse Penetrant Alley", an example for the second type of penetrant alleys, can be found in between Gold Restaurant and the Amei Teahouse; the path leads to the Taro Potato Teahouse and the backyard of The Shi's House, then splits into two paths: one of which connects to Old Windows Teahouse and Mountainous Town Restaurant on QīngBiàn Rd, the other path runs parallel to Jishan St. and leads to its exit. There are two good examples for the third type of penetrant alley: one lies across from the Gongyo Market on Jishan St.; visitors can take it up to reach Jiufen's ShengMing Temple.