1. Natural Stones in Architecture: Introduction

Since the prehistoric age, men have used stone for its unique durability to erect monuments of extraordinary, mostly religious importance. Due to lacking transportation facilities until the 19th century, stones from nearby sources had to be chosen to build churches, castles and towns. Only for exceptional cases were rare and decorative stones like marble transported over long distances when stone of the same color and beauty was not available in the near vicinity. The design of building structures and elements must be adapted to the mineralogical, physical and mechanical properties of stone. The high compressive strength and the low tensile strength of stone require special techniques to overarch gateways and to erect vaults. Mediaeval builders who succeeded in the erection of high and light structures like Gothic church choirs or spires could only stabilize the construction with the help of hidden steel anchors. Only with the emergence of steel and reinforced concrete, the limits that stone properties posed to building structures had been overcome, and a new era of architectural building design began.