At the turn of the twentieth century, life expectancy in Brussels amounted to only 41 years, while the national average was approximately 10 years higher. In other large cities in Belgium, the level was also 5 to 7 years higher than in Brussels. In previous research, we suggested that the most important determinants of the Brussels health penalty were unhygienic working conditions in cottage work and small-scale companies, together with the high levels of crowding and the absence of pure drinking water in many neighbourhoods. As these factors suggest large mortality variations within the city of Brussels, an individual level analysis is required. In this article, we examine whether residence and social class influenced the age at death of the Brussels population. We use individual death certificates for the year 1910 with data on age at death, sex, residence and profession, combined with data on sanitary conditions from the Brussels’ city reports and the special census of habitations conducted in 1910. We perform a linear regression analysis with age at death as dependent variable. Some independent variables such as social class (HISCO classification based on the profession of the deceased, their spouse or parents) and sex are measured on the individual level, while other variables such as the level of crowding, and cadastral class of the inhabited houses are based on street level. To visualize the variation in health conditions and mortality within the city, the results of our regression analysis are complemented by maps. As a result, our study will deliver important insights into the excess mortality of the Belgian capital at the turn of the twentieth century and into the historical debate on social health inequalities.