Haverfordwest was an Augustinian priory founded in the late 12th Century on the bank of the River Cleddau. It was founded by Robert fitz Richard of Haverford, a vassal of William Marshall, earl of Pembroke. In order to be able to make use of the sloped land so close to the river, the priory was constructed on an earthen platform, which rose to a height of 2.5 metres, supported by buttresses. The cramped location between the river and the hillside meant there was little room for the priory to expand over the years, and the main entrance was to the north, since the more usual western arrangement was untenable.

Most of the religious buildings were erected during the early 13th Century, and the limitations of the site meant that it changed little over the course of its existence. It appears to have had a relatively uneventful history, although with the Augustinian monks being less reclusive than other orders, it's known that they were actively engaged with the life of the town.

Following Henry VIII's suppression of the monasteries, the Haverfordwest Priory was surveyed at the beginning of October 1536AD and then dissolved in February 1537AD.

Today, the ruins of Haverfordwest Priory are tucked away and hidden in a quite corner of the town. Unless you were specifically looking for them, they're hard to stumble across. Signposting is limited. The site itself is tranquil and exists as a strangely sedate oasis, overshadowed by the elevated course of the A4076 that runs alongside the far bank of the river. Although not the most impressive of ruins, there's still enough to see to make the site worth a visit.