Lerchenborg manor house near Kalundborg was built in 1704 when the village of Østrup was abandoned, and was originally known as Østrupgård. In 1742, the estate was acquired by General Christian Lerche. In 1743-45 he built the present main building, which is one of the largest and most accomplished Baroque residential designs of its kind in Denmark. It consists of a long, two-storey main wing, long, one-storey side wings, which in turn give onto short side wings. The park contains distinctive clipped avenues and hedges of the same period. The estate belonged to the Lerche family from 1742-1927 and again from 1952 to the present day. It was an entailed estate from 1755 to 1804 and a count's estate from 1818 to 1923.
In the 1700s, much of the landed gentry was deeply in debt. Estate revenues were low because times were unfavourable, the estates were badly run and the tenant farmers were failing to pay what they owed. At the same time, an estate owner had to live extravagantly to make a name for himself. Estate owners were failing to make ends meet. Georg Flemming Lerche certainly had his work cut out. In 1766, he inherited Lerchenborg from a distant relative. Lerchenborg was Zealand's largest estate, wtih six manorsand some 500 farms. Yet the young estate owner was strapped for cash all his life. Lerchenborg was an entailed estate, which meant that it could not be mortgaged, yet Lerche beseeched the king repeatedly for permission to use it as security for a loan. The estate was run more effectively and revenues increased – yet not as rapidly as the debts were run up, and eventually a large portion of it had to be sold off.