Zero-level datum at Alicante City Hall

On the first step of the Alicante City Hall stairway sits Spain’s official zero-level datum, the reference point for all altitude measurements above sea level in the country.

Why a zero datum?

Sea level varies with tides and location, so nations establish a fixed benchmark for consistent altitude surveys.

Spain’s Zero-level Location

• First stair of Alicante City Hall
• Denoted Alicante N.P.1 as the national zero point

Why Alicante?

• Minimal tidal range on its coastline
• 1871 survey linked Madrid’s Observatory to Alicante’s City Hall stairway
• Benchmark fixed at 3.407 m, enabling calculation of Madrid’s zero (625.562 m)

City Hall Architecture

• 18th-c. Baroque palace (1699–1780)
• 49 m façade with three levels and corner towers
• Main entrance on Plaza del Ayuntamiento; rear on Plaza de Santa Faz
• Notable interiors: Blue Hall & Queen Isabella II’s royal chamber

Visit Alicante and stand at the step from which all of Spain’s altitudes are measured: the iconic City Hall stair.