distinctive wooden pavilions on top and embrasures for guns and lookouts. the beacon tower. It has five chimneys to make different signals with smoke or fire. When one was lit it signaled peace, two meant the enemy had been spotted, three warned that the enemy was approaching, four meant the enemy had made it into the city, and five signals lit was an alert that fighting had begun. Poru 砲樓 versus Poru 鋪樓 For an unknown reason, the original Chinese terms (, "fortified tower, blockhouse") and (, "platform") have been alphabetized by the same Hangul , generating several naming collisions. In accordance with the authoritative Hwaseong Seongyeok Uigwe (1801), it is convenient to maintain different names for different kinds of fortification structures. This leads to alphabetize 砲樓 as 'GunTower' and 鋪樓 as 'SentryPost'. The following gallery shows how different these structures are in their design and their usefulness. Features of the Wall There were 48 structures, including those no longer existing, situated along the wall and which can be sorted by their relative usefulness: Main Gates (4): South, East, North, West Flood gates (2): South, North Beacon (1): Beacon Tower Spur (1): South-West Spur (용도) Command Posts (2): East, West Pavillons (4): South-East, North-East, North-West, South-West Guard Platforms (4): South-East, North-East, North-West, South-West Secret Gates (5): South, East, North, West, South-West Observation Towers (3): South, North-East, North-West Sentry Posts (5): East No. 2, East No. 1, North-East, North, West GunTowers (5): East, North-East, North-West, West, South Crossbow Platforms (2): North-East, West Turrets (10): East No. 3, East No. 2, East No. 1, North-East, West No. 1, West No. 2, West No. 3, South-West No. 1, South-West No. 2, South Four of the original structures were not reconstructed; these were the South-East Gate Guard Platform, the South Secret Gate, the South Observation Tower, and the South Floodgate. All four structures were all situated immediately near the South Gate and the presence of the modern roads required for visitors and inhabitants in the area inhibited their reconstruction. The structures of the wall can also be listed in the order they appear by walking the length of the wall, beginning with the South Gate. or the "Asian Historical Architecture". Here, these structures are listed in anti-clockwise order beginning by the South Gate (the access node using public transportation). South Gate (팔달문) South-East Gate Guard Platform (남동적대) South Secret Gate (남암문) South Observation Tower