The Tapuinikau Reserve comprises the remains of the prehistoric-historic pā of Taupuinikau. The site is of high cultural, historic and archaeological heritage value due to its association with significant nineteenth century Māori figures and its high level of structural integrity. Drainage of the former wetland area surrounding this pā has also uncovered a rare carved paepae and a collection of wooden artefacts. The site is notable for the impressive condition of the remaining defensive earthworks, some of which incorporate stone revetments; a relatively rare phenomenon in Māori pā construction. The site also contains an urupā.

The date of the initial construction and occupation of this site is not known, but by the early nineteenth century the pā was one of the key strongholds of the Taranaki Iwi. The site was besieged by a northern taua (war party), led by the important historical figures of Te Rauparaha (Ngāti Toa), Tu-whare (Ngā Puhi) and Muru-paenga (Ngāti Whatua) in 1818. Within the pā at that time were the important Taranaki figures of Kukutai, Te Ra-tu-tonu and Mounga-tu-kau, among others. The siege of the pā was ended when the defenders, with the aid of Te Atiawa members of the besieging taua, abandoned the pā under cover of darkness.

Tapuinukau also appears to have been reoccupied during the first Taranaki Land wars of 1860. However, the site was not attacked by the British.

The pā consists of three hillocks formed by lahars, situated on the northern (right) bank of the Teikaparua (Warea) Stream. A series of concentric terraces surround the upper platforms of these mounds, which are naturally protected on the river flank by a steep drop to the river below. The three hillocks were formerly linked by an outer ditch and bank that enclosed them as a single site. Unfortunately these earthworks were levelled by bulldozing circa 1975. The pā contains numerous storage pits, levelled terraces and house platforms. Sections of stone revetments remain intact and widespread stone deposits on terraces point to more extensive revetments which have since deteriorated.

Tapuinikau was made a Scenic Reserve in 1929, however this area contained only the northernmost and largest of the lahars. It was then designated a Historic Reserve, and the smaller two lahars and an easement from Newall Road were added in 1976. The Taranaki Iwi Claims Settlement Act 2016 revoked the reservation and vested the estate in the trustees of Te Kahui o Taranaki. It is now a privately managed historic reserve.

Tapuinikau has been recorded as two archaeological sites in the New Zealand Archaeological Association (NZAA) site recording scheme. The NZAA site record postdates the bulldozing of the outer earthworks and the recorder was presumably unaware the hillocks were originally a larger, but singular, site. The northern and larger of the mounds is recorded as P20/21, while the smaller two mounds to the south are recorded as P20/22. In reality both sites are components of a single and much larger site.

Drainage of the Kiakia swamp, located immediately north of the pā, uncovered a number of carved wooden artefacts in 1976, now conserved and held at Puke Ariki. Photographic records also held at Puke Ariki show that the wetland was traversed by a wooden causeway. Further finds were uncovered from the same area in 1988; these are also conserved and held at Puke Ariki. Tapuinikau also contains a number of interesting and unusual features other than its archaeological record. Early records note that the site contains vegetation and natural features that have high cultural values to local Iwi.

Today the much of the site remains in excellent condition under the canopy of established bush. Despite the loss of the outer defensive earthworks the scarps and terraces are impressive and clusters of massive open storage pits, over 1.5 metres deep despite being half filled with leaf mould, are particularly notable on the upper platform of the northwest hillock. The site is an excellent field study of the resourceful adaptation of localised landforms into defensive pā sites by prehistoric Māori.