The oldest preserved monument in Ostrov is the Church of St James the Great. Tradition dates the consecration of the church to 1226. This information is not sufficiently documented, but it is quite probable considering the character the entrance portal’s style.
This is a small country church with a right-angled nave and an almost square-shaped presbytery, arched-over in the third fourth of the 13th century. Some hints in the garret and in the gable of the nave point to the possibility that originally, a choir tower was planned to be built over the presbytery. On the northern façade, one enters the church through an archivolt portal dating to 1220-1230. The church, originally the parish church, is listed as the cemetery church beginning in the 16th century. In 1588, the cemetery was expanded. At the beginning of the 17th century, the church is mentioned to be dilapidated. Thus, in 1606, it was completely restored; during this reconstruction, the windows were made larger, and the church received a new roof. Later, the church again fell into disrepair, and at the beginning of the 20th century, it was even designated to be demolished. Luckily, this did not happen (thanks to the efforts of the Heritage Committee of the Imperial and Royal Ministry of Culture and Education and the local parish), and in 1912, the church was fully reconstructed.
In 1937, when whitewashing the church, Renaissance figurative paintings were discovered under several layers of plaster – the figures of two angels, created approximately in the 16th century. Upon closer examination carried out in 1982, elements of early Baroque painting were also found.
In 1990, the original Baroque organ was taken out of the decrepit church, which was then erected and consecrated in 1992 in the Church of St Wenceslas in Milín. The building belonged to the church, which did not have enough financial resources for its maintenance, so it was transferred into the assets of the town of Ostrov, and in 2005, the reconstruction of the church was commenced. In 2010, the interior of the church was fully renewed.