With no electricity to power lights, Rome's churches had two options: candles or the sun. Candles are nice, but in a place that's main purpose is to connect with God, it's best to take advantage of what God has given. Let there be light, divine light.
Or the great architects of these religious monuments just knew what they were doing.
Choose your seat and maybe the light will choose you.
Major cathedral, major light. St Peter's and a sculpture room at the Vatican museum.
Another ray at St Peter's.