Complex sentence: By the turn of the century, Londinium had grown to about 60,000 people, almost certainly replacing Camulodunum (Colchester) as the provincial capital and by the 2nd century, Londinium was at its height.
Split into simpler sentences: By the turn of the century, Londinium had grown to about 60,000 people and almost certainly replaced Camulodunum (Colchester) as the provincial capital. During the 2nd century, Londinium was at its height.