The NAP-zero bolt beneath Amsterdam City Hall

Verified so far

• A Stichting NAP brochure says a pole in the City Hall basement reaches the second sand layer.
• A bronze bolt at its top was adjusted to NAP zero under City and Rijkswaterstaat surveyors.
• The monument was unveiled on 18 May 1988 for the opening of the new City Hall.
• The former NAP Visitors Centre is closed.

Evidence limits

This historical installation is not the original Dam Square point, a replica, a current attraction or the sole operational definition of national NAP. No tours, hours or live water-column operation are advertised.

Sources

1. 1
   Stichting NAPNAP monument brochure ↗ (opens externally)
2. 2
   Stichting NAPVisitor centre status ↗ (opens externally)
3. 3
   RijkswaterstaatHistory of NAP ↗ (opens externally)