St. Patrokli is of great example of Romanesque architecture in Westphalia. In 960, Bruno I, Archbishop of Cologne transferred relics of St. Patroclus from Troyes to Soest. Since 964, they have been housed in the church.
The original building, with a monumental westwerk, was completed before 1000. In the first half of the 11th century, the westwerk was rebuilt after a fire. The altar was consecrated on in 1118 and St. Stephen's chapel in 1149. In a further phase of construction a large hall crypt, the apse and a vaulted choir were installed. The Mary choir, the paradise and the East cloister were also built. The nave and the transepts were vaulted and the whole interior received painted decoration. This phase of construction ended in 1166. The western portion of the building was rebuilt from the last quarter of the 12th century and into the 13th century. The old westwerk was made to appear part of the nave by the removal of supports, partitioning, and the installation of new vaulting in the last one and a half bays.
The crypt was blown up in 1817. During an aerial attack in 1944, the north side of the westwerk and vaults were severely damaged. In the aerial attacks of 1945, the organ was destroyed, the apse was obliterated and there was severe damage to the spire and vaulting. The reconstruction began with the laying of the groundstone in 1949. By 1954, a new high altar had been erected, and the vaults and apse had been repainted. The southern cloister and the eastern and southern wings were renovated. The local painter Hans Kaiser created windows for the westwerk and secondary crypt.References:
The Kalozha church of Saints Boris and Gleb is the oldest extant structure in Hrodna. It is the only surviving monument of ancient Black Ruthenian architecture, distinguished from other Orthodox churches by prolific use of polychrome faceted stones of blue, green or red tint which could be arranged to form crosses or other figures on the wall.
The church is a cross-domed building supported by six circular pillars. The outside is articulated with projecting pilasters, which have rounded corners, as does the building itself. The ante-nave contains the choir loft, accessed by a narrow gradatory in the western wall. Two other stairs were discovered in the walls of the side apses; their purpose is not clear. The floor is lined with ceramic tiles forming decorative patterns. The interior was lined with innumerable built-in pitchers, which usually serve in Eastern Orthodox churches as resonators but in this case were scored to produce decorative effects. For this reason, the central nave has never been painted.
The church was built before 1183 and survived intact, depicted in the 1840s by Michał Kulesza, until 1853, when the south wall collapsed, due to its perilous location on the high bank of the Neman. During restoration works, some fragments of 12th-century frescoes were discovered in the apses. Remains of four other churches in the same style, decorated with pitchers and coloured stones instead of frescoes, were discovered in Hrodna and Vaŭkavysk. They all date back to the turn of the 13th century, as do remains of the first stone palace in the Old Hrodna Castle.
In 2004, the church was included in the Tentative List of UNESCO"s World Heritage Sites.