* The earliest known glass dates from Egypt in around 2500BC.
* Glass blowing began in Syria 2,000 years ago.
* Safety glass was patented in 1909.
* Glass is made from the fusion of sand at high temperatures.
* Window glass is not a liquid or a solid.
* Window glass is flowing, albeit incredibly slowly, which is why old windows are thicker at the bottom than the top.
* Elizabethan glass was so expensive people often took their windows when they moved.
* The bullseye in old glass is where the blowing pipe was cut off.
Wood facts * Trees use the Sun's energy to turn liquid water and carbon dioxide gas into wood through photosynthesis.
* Wood cells are added to trees during the summer, thickening the trunk and producing "growth rings".
* Pine is often used for window frames. Oak, cypress, male, walnut and birch are used for staircases, floors and doors.
* Cladding may be made from redwood or cedar which produce weather-proofing oil.
Brick facts * House bricks absorb water.
* The earliest known brick houses were built in Jericho (Palestinian West Bank) 12,000 years ago. 3,000 years later they were first fastened with mortar.
* The first kiln-fired bricks were made in Mesopotamia around 3000BC.
concrete facts * Concrete is a mixture of cement, sand and gravel.
* Cement is made by burning lime and clay which sets like stone when mixed with water.
* The first known concrete was from around 200BC in the Roman town of Palestrina in Italy.
* Reinforced concrete was invented in the mid-19th century.
* Pre-stressed concrete - reinforced with metal bars - was invented in 1886.