The RCH Institute of History has published the newest volume of the serial Monumenta Hungariae Historica entitled „Mosques in Ottoman Hungary” by Balázs Sudár, research fellow of the Institute of History. The great work (more than 650 pages, with 225 pictures, and detailed indexes) contains the description of 450 Muslim places of worship existed in Hungary under 150 years of Ottoman rule. The author collected and compared all kinds of sources concerning this topic during his large-scale research. The Muslim places of worship were not only religious institutions but also the centres of cities and settlements and the places of community life, and also regional economic centres. Mosques played determining roles in the life of the settlements, so their history may provide important information about the life of Hungary under Ottoman rule.