Answer the following question in 3-4 complete sentences.

Answer:

A post-and-lintel system uses vertical posts which are separated to support a horizontal beam. The main problem that can occur with a post-and-lintel system is cause by the weight is unevenly distributed and the center is unsupported, which can cause sagging over time. Stonehenge is an example of an ancient structure that used a post-and-lintel system.