These laterite fortresses are in the location of interior city wall area housed in the corner of the city in all 4 directions such as southwest corner fortress, northwest corner fortress, northeast corner fortress and southeast corner fortress (the southeast corner fortress is now disappeared) All fortresses have the landscapes in a rhombus shape equipped with acute arrow-like angles that are sticking out to the moat. The bases were built as a high version of core bases and slightly sloped up while the battlements were set up on the top part of the walls. Also, the stairs to the fortresses were built interior.

It is a fortress made of laterites on the inner city wall at south side between southwest corner fortress and Dan gate. The east side of the fortress is next to Chao In gate. The fortress plan is in a pentagon shape with arrowhead and heading to the inner moat. The beetle peak is 14.50 meters wide and 19 meters long from the wall and it is 7.70 meters high. The fortress is built from laterites and slightly slopes up. All-round top consists of battlements together with the stairs to the fortress which is 2.70 meters tall.

Another laterite fortress is located on the mound among the moats at the south which is direct to Dan gate. The fortress plan is square with 15 meters wide of each side. Only a gate of 2.50 meters wide was built for entering and exiting which is embedded in the middle of the north wall facing to Dan gate. There are two 1.40-meter-wide holes built in each inner side of the fortress wall. Those were supposed to be for housing the cannons.

This gate is made of laterites located on the west at the middle of the inner city wall between southwest corner fortress and northwest corner fortress. The gate features 3.60 meters of the width and 4.50 meters of its height. Inside, 2 sides of the battlements at the gate are equipped with the staircase to the top.

There was a mention for Hua Muang gate in second royal archives composition by King Chulalongkorn the Great (Rama V) for his personal trip that “…Next, there is a gate called Hua Muang gate. This gate was presumed to be a triumphal arch by Crown Prince but I don’t think so because there’s not on exactly the north. As I can see, 2 fortresses are stuck with the gate on the sides…”