The Ronneburg castle was one of the most magnificent strongholds of the Archbishopric of Riga. The first mention of it comes from 1381, but its construction had to start much earlier, probably in the third quarter of the thirteenth century. Most often, the year 1262 is accepted, mentioned in early modern sources. Like other bishop’s castles, Ronneburg has been occupied several times by the Teutonic Order army, but this has not led to major damages to the building. In the fifteenth and sixteenth century fortifications of the castle were expanded and adapted to use firearms. The most serious works were carried out under the rule of archbishop Jasper Linde at the beginning of the sixteenth century. However, it did not protect the stronghold from subsequent damages. In 1556, the Teutonic army and then the Moscow troops occupied Ronneburg. After their expulsion, the castle became a part of the Polish–Lithuanian Commonwealth. In the 17th century it was the subject of battles between Poland, Sweden and Russia, which led to the most severe ravages in 1657-1658. In 1683, the Swedish authorities removed Ronneburg from the list of fortifications and ordered to dismantle most of its fortifications.
The castle from the fourteenth century had a single courtyard with a rectangular shape, with three wings of buildings. The undeveloped north side was protected only by a single wall, in the western part of which was a gate. Next to it, in the north-west corner of the castle, a huge four-sided tower was erected, which was the most important element of the defense system. The representative rooms were located on the first floor, in the south wing were two refectars, in the west wing guest rooms or private rooms of the bishop, while the east wing housed a large audience hall and a chapel in the northern part. The communication was provided by an external cloister, originally wooden, then made of stone. The element distinguishing the upper castle from other episcopal and teutonic strongholds was the partial use of wood at the elevation of the upper storeys of the castle and a one-sided roof descending inwards, instead of the traditional gable form.
From the north-east side of the upper castle stretched, at first not fortified, an outer bailey. In the 15th and 16th centuries, along with the entire castle, it was fortified with a new ring of walls, equipped with at least five semicircular towers, three of them from the south, and one from the west and north – east. The new fortifications separated the area of the economic ward, which in addition was covered from the north and east by another, lower external wall. Its extension also protected the upper castle from the three other sides, where it did not touch the outer bailey. As a result, a large zwinger was created around the castle, on which grounds economic, guards and service buildings also grew. An additional element of the defense was the south-west, free-standing tower and fish ponds guarding the castle from the south and east, fulfilling the function of a moat. An unconventional solution was the main entrance to the castle, led partly underground, in the length of the outer eastern wall.
Because the demolition works from the 17th century covered mainly defensive elements, large fragments of the representative part of the upper castle have survived. There is also a lower part of the main, four-sided tower, maintained approximately to the level of the third floor. Only small, stone relics preserved of the outer bailey and external fortifications.
Borowski T, Miasta, zamki i klasztory, Inflanty, Warszawa 2010.