Simplify the following text for a Grade 10 native English-speaking person.
Original: A great number of ecclesiastical buildings remain from this period , of which even the smallest are often structures of architectural distinction while many of the larger churches are considered priceless works of art and are listed with UNESCO as World Heritage Sites . For this reason a study of Gothic architecture is largely a study of cathedrals and churches .
Simplified: Even the smallest Gothic churches are often very beautiful , while many of the larger churches and cathedrals are thought to be priceless works of art .