Roman groma
Groma romana
- Date
- c. 150 BCE · confidence low
- Place
- Rome, Latium, Italy
- Credited to
- Roman land surveyors
- Field
- Knowledge & symbols
⚠️ Disputed: the sources disagree.
What it is
A surveying instrument with two rods crossed at right angles and four plumb lines, used to lay out perpendicular lines on the ground. With it the cardo and decumanus of Roman fields and cities (centuriation) were set out.
It is known from the gromatici texts and from a groma found at Pompeii (1st century AD); its origin is probably Mesopotamian or Greek and the date is approximate.
What it led to
- centuriation of the Roman countryside and the layout of colonies
- grid-plan cities of the Empire
- the medieval land-surveying tradition (gromatici)