Sunday 

Sunday is named after the Sun, or perhaps after the Sun God. 

In most calendars Sunday is the 1st Day of the Week but in some calendars it is the 7th day of the Week.

Considered by Christians to be the Day of rest and worship which is referred to as the Sabbath.  Was Sunday chosen because Christianity appears to many to simply be a modified version of Sun Worship?

It seems odd to me that Christianity would pick their Day of worship to be the on the Day of the Week named for the Sun God, unless perhaps, the person of Jesus Christ is the Christian idea representing the Sun (Son of God or perhaps Sun of God).  Not that it matters what day the week starts on.