Simplify the following text for a Grade 12 native English-speaking person.
Original: It grew to be one of the most important Roman colonies in modern-day Switzerland , with a forum , a basilica and an amphitheater that was discovered only recently , in 1996 , when digging for the construction of a new building .
Simplified: It grew to be one of the most important Roman colonies in modern-day Switzerland , with a forum , a basilica and an amphitheater that was discovered in 1996 .