Lais Monastery Castle was founded as a Teutonic Order stronghold in the Middle Ages, although the exact date of its construction is unknown. It may have existed prior to 1406, when it was first mentioned in historical sources, as the town itself appears in records as early as the beginning of the 14th century. This border stronghold guarded the northern section of the border between the territories of the Order of the Knights of the Sword and the Duchy of the Bishops of Dorpat, and was administratively subordinate to the commandery at Felin. Initially of rather marginal importance, the stronghold at Lais was thoroughly rebuilt in the 15th century (as Livonia faced a greater threat from Moscow) and adapted for the use of firearms. At that time, as part of the reconstruction of the fortification system, massive towers were erected at the corners of the stronghold. A mighty artillery tower on the north-western side, with a diameter of 14 metres and walls 4 metres thick, became a key defensive point. Despite this modernisation, Ivan the Terrible’s forces captured and partially destroyed the castle in 1559. In 1582, under the terms of the truce with Jamie Zapolski in Lais (or Lajs), the northernmost starosty of the Polish-Lithuanian Commonwealth, belonging to the Dorpat Voivodeship, was established. According to the nineteenth-century *Geographical Dictionary of the Kingdom of Poland*: ‘The non-fortified Lajs starosty in the Duchy of Livonia, according to the Crown registers, consisted of the defensive castle of Lajs and the adjacent estates. King Stephen Báthory, following the liberation of Livonia, granted this starosty to Andrzej Orzechowski in recognition of his valour, whilst King Sigismund III, by a privilege dated 7 November 1589, confirmed his possession of this starosty”. The period of Polish administration of Lais Castle should be regarded as beneficial for the development of the area. During the tenure of Starost Andrzej Orzechowski, the ruined castle was rebuilt, and a new settlement, home to over 200 people, was established in the outer bailey. The settlers brought to Lais were mainly refugees from the Swedish part of Estonia, where living conditions for the lower social classes were rather harsh. In the settlement, on the initiative of the Polish authorities (and presumably under the influence of the Jesuit college then operating in Dorpat), a small wooden Catholic church and a rectory were built. The next Polish–Swedish war, which broke out again in 1600, soon engulfed Livonia. In the autumn of that same year, Swedish troops began a four-week siege of the castle at Lais. The Polish garrison defending the castle surrendered only after the death of the gravely ill Starost Orzechowski. A year later, the castle was once again in Polish hands and remained the centre of the starosty until the winter of 1622. The final destruction of the northernmost stronghold of the First Polish Republic took place during the Great Northern War at the beginning of the 18th century. It is worth noting that between 1700 and 1701, the Swedish King Charles XII had his winter residence at the castle.

The ruins of Laiuse Castle are situated approximately 3 km from the centre of the present-day town. In its current state, the former stronghold survives as an impressive, yet increasingly dilapidated ruin. In the autumn of 2023, construction and restoration work was underway on the western curtain wall of the defences. This part of the structure, with its centrally situated entrance gate and the remains of the so-called artillery tower in the north-western corner, is the best-preserved section of the medieval stronghold. Understanding the layout of the former defensive complex of Lais Castle is facilitated by the preserved, freestanding sections, each over a dozen metres long: the southern curtain wall and the remains of the tower in the north-eastern corner. The infrastructure of the former castle grounds is utilised for local outdoor events. During the ‘Polish Days’ celebrations at Laiuse Castle in the summer of 2003, attended by representatives of the Polish Embassy in Tallinn, a ceremony was held to unveil a commemorative information plaque entitled ‘The Polish Era in Laiuse (1582–1622)’. The plaque currently in place, situated by the access road just before the castle ruins, is a replacement (the original was destroyed). The history of the site is described in Estonian, English and Polish, illustrated by the coat of arms of the First Polish–Lithuanian Commonwealth: the crowned Polish Eagle and the Lithuanian Pogoń. In the south-western part of the village, near the parish church of St George (now Lutheran), which traces its origins back to a medieval church, lies the former local cemetery. The entrance to the cemetery leads through a pointed-arch gate made of brick and stone. The oldest gravestones date from the 19th century, though most are in a state of disrepair. Determining whether any Polish gravestones have survived within the cemetery requires further inventory work.