Look at this page for suggestions of or ideas on possible topics in Roman history that you can make a documentary on.
The Pont du Gard is the most famous part of the Roman aqueduct which carried water from Uzès to Nîmes until roughly the 9th century when maintenance was abandoned.
1866 depiction of View on the Forum Romanum from left: Temple of Saturn, Temple of Vespasian, Rostra, Temple of Concord, Arch of Septimius Severus and Tabularium in background