As long as 2343 (79 miles) football pitches
The Roman Emperor.. .. since I guess you mean the Emperor who built the Wall in Britain..
Dacia, Nabataea, Arabia.
A river can be as long as a country! For example the Mississippi River is almost as long as the U.S vertically.
The river Alt is 28kilometers long.
The Charles River is about 81mi long.
The River Wharfe is a river in Yorkshire, England and is 60 miles long.
the river nile it is 6695 km long
The Missouri River is 2,341 miles long and is the longest tributary to the Mississippi River.
River crouch is 17.5 miles long
The Benue River Is 1400 Km Long
The Roe River is 12.6 meters long!
The Ebro river is 298 km long.