Simplify the following text for a Grade 11 native English-speaking person.
Original: Furthermore , this cathedral contains examples of some of the earliest and best Quattrocento paintings of the Iberian Peninsula , by artists from Rome engaged by the Valencian Pope Alexander VI who , when still a cardinal , made the request to elevate the Valencian See to the rank of metropolitan see , a category granted by Pope Innocent VIII in 1492 .
Simplified: The cathedral also contains examples of some of the earliest and best Quattrocento paintings of the Iberian Peninsula . These were brought from Rome via artists commissioned by the Valencian Pope Alexander VI .