No one knows how old spirit levels really are. However, it is known that the Romans used water filled tanks as primitive spirit levels when building their famous aqueducts.
By studying the water surface mode in the vessel, the Romans could determine if the base was completely flat or at an angle.

To find a more modern tool we need to travel to 1661 when the French scientist Melchisedech Thévenot invented the modern spirit level. Although, it took til the beginning of the 18th century before the invention spread.
For a long time though, many builders still preferred old bottles with water and used these as a sort of spirit level.
Nowadays, spirit levels do not contain water, but alcohol or oil.

The spirit level consists of a profile, a horizontal vial, one or two vertical vials and end caps.
There are spirit levels for a wide variety of purposes from building stairs and laying pipes, to applying tiles and checking that the caravan is standing straight. When selecting spirit levels, there are several important factors to consider, in addition to the main purpose.