The NAP origin point beneath Dam Square

What the sources establish

• Rijkswaterstaat says the original NAP zero point lies in the middle of Dam Square.
• It is hidden beneath a stone marked “NP XXX” in front of the Royal Palace.
• NAP became a nationwide reference under King Willem I in 1818.
• The modern network uses more than 35,000 surface benchmarks and roughly 400 underground marks.

Evidence limits

No brass bolt, pile depth, construction detail, public access or present operational primacy is invented. The historic origin is not conflated with one active national control mark.

Sources

1. 1
   RijkswaterstaatHistory of NAP ↗ (opens externally)