Mao hills Observatory is located on the Hong Kong Tseung Kwan O, Sai Kung Mao hills, hikers and neighborhood called Mau Wu spent fort, do not test year of construction, but the existing historical documents is estimated that the building as early as in 1898 the British leased the New Territories before completion, it estimated at Observatory Island Qing Dynasty temple customs, for observation purposes temple door channel. Based on its unique, observatory has been listed as a historical building Antiquities and Monuments Office.

Mao Koyama Island observatory and the temple customs are closely linked, can observatory to monitor the situation throughout the continent and its waters the vessel out of the temple, the official estimate was observatories through the lights, and fireworks, or through, the temple Island Contact headquarters and customs vessels.

At present, Mao hills, ruins include the lower half of a round stone tower and a rectangular rustic-style stone house. The construction of two buildings chosen by dark gray volcanic rock, it is estimated from the nearby local mining. Round Tower should be a watchtower, observers can observe the temple door unhindered through the windows semicircular channel. The original two-high tower, the second layer has now collapsed, an existing stairway stone, through to the second floor has been collapsed. Historical photos show a similar domed towers of the original Chinese hat, the top portion of the current no longer exists, for unknown reasons. All doors and windows have been lost, leaving only the stone window and door frames. Building collapse debris has already been removed District Council, as a small part of the construction of open bench. After a single storey tower is estimated to be stationed in the building official headquarters or domicile to the local rural village house model design, and round tower style is very different. At present, the ceiling of the building has collapsed.

Circular tower design reminiscent of the ancient circular stone fort or castle coast with Europe defense, is extremely rare in Hong Kong, a similar circular tower and lighthouse building is only found in several former Marine Police Headquarters in Tsim Sha Tsui, Hong Kong timekeeping tower, in addition there are the two observation tower Stonecutters barracks, but they are octagonal building rather than round; NT observation tower also has many villages, but they are mostly built in brick, is more square shape.

Scenic Area Address: on the Tseung Kwan O, Sai Kung, Hong Kong Wu Shan Mao

Bus routes: Take n691 Road; KMB 93a, 93k, 93m, 95m, 95,98a, 98c, n293 Road