[3] Among the owners of the village were the noble families of Dubá, Kostka of Postupice, Šelenberk and Waldstein.

In 1745, Ondřejov was promoted to a market town, but it lost the title after World War II.

In 1898–1906, the industrialist Josef Jan Frič built an astronomical observatory in the village, which he gave to the Charles University in 1928.

Today the Ondřejov Observatory is operated by the Astronomical Institute of the Czech Academy of Sciences.

[7] The Church of Saints Simon and Jude was originally a Romanesque building, modified in the Baroque style in 1668.