There have been 16 popes named Gregory so you need to be specific.
No. Pope Gregory VII in 1079AD decreed the practice.
No, Pope Gregory the Great .was also known as Pope Gregory I.
The Gregorian calender is named after Pope Gregory XIII who made its use official in a papal decree in 1582.
That would be Pope Saint Gregory I.
Pope St. Gregory VII was pope in 1075.Pope St. Gregory VII was pope in 1075.
Yes, Pope Gregory I was the 64th pope.
Pope Gregory I
Yes, he was also known as Pope Gregory the Great.
Pope Gregory VII was a Catholic pope. Of course he was a Christian.
Pope Gregory VII was elected pope on April 23, 1073.
Pope Gregory III was born in 690.
Pope Gregory XII was born in 1326.