
In Roman
urban planning
Urban planning (also called city planning in some contexts) is the process of developing and designing land use and the built environment, including air, water, and the infrastructure passing into and out of urban areas, such as transportatio ...
, a ''decumanus'' was an east–west-oriented road in a
Roman
Roman or Romans most often refers to:
*Rome, the capital city of Italy
*Ancient Rome, Roman civilization from 8th century BC to 5th century AD
*Roman people, the people of Roman civilization
*Epistle to the Romans, shortened to Romans, a letter w ...
city or ''
castrum
''Castra'' () is a Latin language, Latin term used during the Roman Republic and Roman Empire for a military 'camp', and ''castrum'' () for a 'Fortification, fort'. Either could refer to a building or plot of land, used as a fortified milita ...
'' (military camp).
The main ''decumanus'' of a particular city was the ''decumanus maximus'', or most often simply "the ''decumanus''". In the rectangular street grid of the typical Roman
city plan, the ''decumanus'' was crossed by the perpendicular ''
cardo
A ''cardo'' (: ''cardines'') was a north–south street in Ancient Rome, ancient Roman cities and military castra, camps as an integral component of Urban planning, city planning. The ''cardo maximus'', or most often the ''cardo'', was the main ...
'', a north–south street.
In a military camp, the ''decumanus'' connected the Porta Praetoria (closest to the enemy) to the
Porta Decumana
''Castra'' () is a Latin term used during the Roman Republic and Roman Empire for a military 'camp', and ''castrum'' () for a 'fort'. Either could refer to a building or plot of land, used as a fortified military base.. Included is a discuss ...
(away from the enemy).
In the center – called
groma – of a city or ''castrum'', the ''decumanus maximus'' crossed the perpendicular ''
cardo
A ''cardo'' (: ''cardines'') was a north–south street in Ancient Rome, ancient Roman cities and military castra, camps as an integral component of Urban planning, city planning. The ''cardo maximus'', or most often the ''cardo'', was the main ...
maximus'', the primary north–south road. The
forum
Forum or The Forum may refer to:
Common uses
*Forum (legal), designated space for public expression in the United States
*Forum (Roman), open public space within a Roman city
**Roman Forum, most famous example
* Internet forum, discussion board ...
was normally located close to this intersection.
Etymology
''Decumanus'' or ''decimanus'' was the
Latin
Latin ( or ) is a classical language belonging to the Italic languages, Italic branch of the Indo-European languages. Latin was originally spoken by the Latins (Italic tribe), Latins in Latium (now known as Lazio), the lower Tiber area aroun ...
word for 'tenth'. This name is said to come from the fact that the ''via decumana'' or ''decimana'' (the "tenth") separated the Tenth
Cohort
Cohort or cohortes may refer to:
Cohort Sociological
* Cohort (military unit), the basic tactical unit of a Roman legion
* Cohort (educational group), a group of students working together through the same academic curriculum
Scientific
* Cohort ...
from the Ninth in the legionary encampment, in the same way as the ''via quintana'' separated the Fifth Cohort from the Sixth.
Examples

Barcino, Barcelona
In the ancient Roman city of
Barcino (present day
Barcelona
Barcelona ( ; ; ) is a city on the northeastern coast of Spain. It is the capital and largest city of the autonomous community of Catalonia, as well as the second-most populous municipality of Spain. With a population of 1.6 million within c ...
, Spain), the ''decumanus maximus'' started at the late-Roman gate (which still stands) in front of the current ''Plaça Nova'' square.
Within the city of
Split
Split(s) or The Split may refer to:
Places
* Split, Croatia, the largest coastal city in Croatia
* Split Island, Canada, an island in the Hudson Bay
* Split Island, Falkland Islands
* Split Island, Fiji, better known as Hạfliua
Arts, enter ...
, in present-day
Croatia
Croatia, officially the Republic of Croatia, is a country in Central Europe, Central and Southeast Europe, on the coast of the Adriatic Sea. It borders Slovenia to the northwest, Hungary to the northeast, Serbia to the east, Bosnia and Herze ...
, is the UNESCO Roman monument,
Diocletian's Palace
Diocletian's Palace (, ; ) is an ancient Roman palace and fortress complex built at the end of the third century AD by the Roman Emperor Diocletian as his retirement residence. About half of the complex was for Diocletian's personal use, with th ...
. This city, built by the Emperor
Diocletian
Diocletian ( ; ; ; 242/245 – 311/312), nicknamed Jovius, was Roman emperor from 284 until his abdication in 305. He was born Diocles to a family of low status in the Roman province of Dalmatia (Roman province), Dalmatia. As with other Illyri ...
, exhibits the characteristic Roman orthogonal street system with the ''decumanus maximus'' connecting the west Iron Gate to the east Silver Gate.
Gadara, Jordan
In Roman
Gadara
Gadara ( or ; ), in some texts Gedaris, was an ancient Hellenistic city in what is now Jordan, for a long time member of the Decapolis city league, a former bishopric and present Latin Catholic titular see.
Its ruins are today located at Umm ...
, present-day
Umm Qais
Umm Qais (), also known as Qays, is a town in northern Jordan principally known for its proximity to the ruins of the ancient Gadara. It is the largest city in the Bani Kinanah Department and Irbid Governorate in the extreme northwest of the co ...
, in
Jordan
Jordan, officially the Hashemite Kingdom of Jordan, is a country in the Southern Levant region of West Asia. Jordan is bordered by Syria to the north, Iraq to the east, Saudi Arabia to the south, and Israel and the occupied Palestinian ter ...
, the ''decumanus'' runs east–west for approximately one kilometre with its ancient
flagstone
Flagstone (flag) is a generic flat Rock (geology), stone, sometimes cut in regular rectangular or square shape and usually used for Sidewalk, paving slabs or walkways, patios, flooring, fences and roofing. It may be used for memorials, headstone ...
s extant.
Damascus, Syria
Another fine example is the
Straight Street or
Via Recta in
Damascus
Damascus ( , ; ) is the capital and List of largest cities in the Levant region by population, largest city of Syria. It is the oldest capital in the world and, according to some, the fourth Holiest sites in Islam, holiest city in Islam. Kno ...
, which is 1,500 metres long, connecting the eastern and western gates.
Beirut, Lebanon
In
Beirut
Beirut ( ; ) is the Capital city, capital and largest city of Lebanon. , Greater Beirut has a population of 2.5 million, just under half of Lebanon's population, which makes it the List of largest cities in the Levant region by populatio ...
's
central business district
A central business district (CBD) is the Commerce, commercial and business center of a city. It contains commercial space and offices, and in larger cities will often be described as a financial district. Geographically, it often coincides wit ...
,
Rue Weygand
Rue Weygand is a street in Beirut's Beirut Central District, Central Business District. Originally, the street was named Rue Nouvelle as it was a new thoroughfare constructed as part of a modernization plan in 1915. Upon its completion, the s ...
, which runs east–west, still follows the ancient
Roman
Roman or Romans most often refers to:
*Rome, the capital city of Italy
*Ancient Rome, Roman civilization from 8th century BC to 5th century AD
*Roman people, the people of Roman civilization
*Epistle to the Romans, shortened to Romans, a letter w ...
''decumanus''.
In Florence, the ''decumanus'' is preserved as the streets Via Strozzi, Via Speziali, and Via del Corso in the city's old centre. Although these streets have different names, they form a continuous line with a split between the Via Strozzi and Via Speziali by the Palazzo Strozzi. In Roman times, these three streets formed the ''decumanus'' of Florentina, the name of the Roman ''
colonia''. The Via Roma and the Via Calimala are formed from the ancient ''cardo'', and what was once the forum in ancient Florence is now the Piazza della Repubblica.

In
Naples
Naples ( ; ; ) is the Regions of Italy, regional capital of Campania and the third-largest city of Italy, after Rome and Milan, with a population of 908,082 within the city's administrative limits as of 2025, while its Metropolitan City of N ...
, there still exist three main ''decumani'' which are, from north to south:
Fondazione GB Vico
, entry on Decumani.
* Superiore: consisting of Via Sapienza, Via Pisanelli, and Via Anticaglia;
* Maggiore: Via dei Tribunali;
* Inferiore: Via Spaccanapoli, consisting of Via Benedetto Croce and Via San Biagio dei Librai.
Gallery
File:Calleva Atrebatum plan.png, Plan of Silchester
Silchester is a village and civil parish about north of Basingstoke in Hampshire. It is adjacent to the county boundary with Berkshire and about south-west of Reading.
Silchester is most notable for the archaeological site and Roman town of ...
, England
File:Roman Cologne, reconstruction.JPG, Plan of Roman Cologne
Cologne ( ; ; ) is the largest city of the States of Germany, German state of North Rhine-Westphalia and the List of cities in Germany by population, fourth-most populous city of Germany with nearly 1.1 million inhabitants in the city pr ...
File:NeapolisStenopoi.jpg, Ancient Naples
Naples ( ; ; ) is the Regions of Italy, regional capital of Campania and the third-largest city of Italy, after Rome and Milan, with a population of 908,082 within the city's administrative limits as of 2025, while its Metropolitan City of N ...
, ''decumani'' in red
File:Ostia antica 64.JPG, Sign indicating the ''decumanus maximus'' in Ostia Antica
Ostia Antica () is an ancient Roman city and the port of Rome located at the mouth of the Tiber. It is near modern Ostia, southwest of Rome. Due to silting and the invasion of sand, the site now lies from the sea. The name ''Ostia'' (the pl ...
File:Ostia Antica 2013-03-08-64.jpg, Ostia Antica, near Rome
References
{{Reflist
See also
Cardo Maximus
A ''cardo'' (: ''cardines'') was a north–south street in ancient Roman cities and military camps as an integral component of city planning. The ''cardo maximus'', or most often the ''cardo'', was the main or central north–south-oriented str ...
External Resources
Exhaustive list of Roman decumanus maximus
Ancient Roman city planning
Ancient city of Rome
Streets in Naples