Images reveal 'lost' Roman city
Aerial photographs have revealed the streetplan of a lost Roman city called Altinum, which some scholars regard as a forerunner of Venice.
The images reveal the remains of city walls, the street network, dwellings, theatres and other structures.
They also show a complex network of rivers and canals, revealing how the people mastered the marshy environment in what is now the lagoon of Venice.
Details of the research have been published in the journal Science.
Andrea Ninfo and colleagues from Padua University, Italy, made the first detailed reconstruction of the city's topography and environmental setting.
This was assembled using visible and near-infrared aerial photographs of the farmlands that currently cover the region, along with a computer model of the local terrain.
The photos were taken during a severe drought in 2007, which made it possible to pick up the presence of stones, bricks and other solid structures beneath the surface.
The authors note that Altinum is the only large Roman city in northern Italy - and one of the few in Europe - that has not been buried by medieval and modern cities.
The results show that the city was surrounded by rivers and canals, including a large canal that cut through the centre of Altinum, connecting it to the lagoon.
Two gates or bridges were built into the walls encircling the city, providing further evidence of how the city's residents adapted to their marshy surroundings.
The researchers were also able to see harbour structures at the edge of the lagoon.