This document discusses two approaches for inferring the construction year of buildings based on topographic maps: a national maps approach and a statistical approach. The national maps approach deduces construction years by analyzing building depictions on maps from 1950-2020, achieving 84.7% accuracy within ±5.8 years. The statistical approach complements missing data and models urban growth patterns, determining construction years with 95% accuracy within ±15.6 years. Both approaches were validated against Switzerland's register of buildings and dwellings.