The key breakthroughs in Gothic architecture occurred inside this confined area, in the succession of cathedrals erected during the 12th and 13th centuries. 2. The supernatural nature of medieval ecclesiastical architecture was given a unique expression in the Gothic church. Where traditional Roman buildings were constructed of brick or stone, the Gothic church was primarily wood. The new style of building required extensive use of iron nails and screws to connect the huge number of wooden parts together. The word "Gothic" comes from the German name for the people who built the churches they stained a "Gothic blue" or "gray". 3. The main purpose of a cathedral was as a place of worship. It usually included a large nave with side aisles, a choir with an elevated seat for the priest, a bell tower, and sometimes other structures such as a baptistery or museum. Cathedrals were built over a long period of time in different parts of Europe, using materials available at the time. They generally follow a similar plan but each one is unique. There are many theories about how cathedrals were built but most involve teams of workers led by a master mason. 4. During the 12th century, monks from various religious orders worked together to build hundreds of monasteries across Europe.