Misc: Give me the matematical constant pi with 15 decimals?

Questions

The main circle and trilithons at Stonehenge are built of which rock?

From which prison in South Africa was Nelson Mandela released?

In the Bible, who was credited with killing tens of thousands of the Philistines, when his king was only credited with killing thousands of the Philistines?

Which star appears brightest in the northern constellation Lyra -it is also the fourth brightest in the night sky?

What avenue runs along the east side of Central Park, New York?