The benchmark is anchored into the stone wall of a house, which was intentionally selected for its proximity to the Velence Mountains' stable granite base.
It provides the vertical datum known as the Nadap system, which replaced the previous system based on the Adriatic Sea level at Trieste.
The marker is a small, unassuming brass or metal stud that has survived over 150 years of environmental exposure.
It is technically classified as the 'Principal Leveling Benchmark of Hungary'.
The location was deemed geologically 'quiet,' meaning it experiences minimal tectonic movement, ensuring the accuracy of national height measurements.
The Nadapi szintezési ősjegy serves as the fundamental geodetic reference point for the entire Hungarian national height system. Established in the 19th century, this primary leveling benchmark defines the 'zero' altitude used for all elevation measurements and official topographic maps across the country. The marker is protected as a historical industrial monument and is located within the wall of a local residential building. It was chosen for its exceptional geological stability, sitting on the solid granite bedrock of the Velence Mountains. Surveyors periodically verify the stability of the stone, which remains the master reference for the Adriatic Sea-level height datum (the Nadap datum). It represents the intersection of science, history, and national infrastructure, acting as the bedrock of Hungarian cartography.
Close-up of the metal benchmark and the accompanying information plaque on the wall.
The marker is located on a public street; please respect the privacy of the residents living at the property.
Combine your visit with a hike in the nearby Velence Mountains to see the geological landscape that makes this location stable.
Read the informational plaque nearby to understand the technical history of Hungarian geodetic surveys.
Do not mistake this for a large museum or grand monument; it is a discreet, small scientific marker.
Maintain a quiet volume and do not touch or attempt to tamper with the benchmark itself.
