The Arch of Titus was build in 82 AD by emperor Domitian just after the passing of his older brother Titus.
It is the oldest surviving arch in Rome and commemorates Titus’ victories, which includes the 70 AD siege of Jerusalem.
It is situated in the NW end of the forum on the Via Sacra, the ancient road that runs through the forum, at its highest point.
There is another image of it in my Rome by Night gallery taken from the opposite side.