This paper tracks the origins and inner changes of Barcelona's economic elite in the long term. The objective is to achieve a deeper understanding of the mechanism that families and individuals developed to gain access to the elites and retain their economic position. For doing so, the paper analyzes industrial and real estate tax payers in three moments (1853-1883-1919). Through this approach we can observe that in aggregate, elites -identified as the 5% of the higher taxpayers- move from a stationary state to a progressive increase of wealth concentration. For a deeper understanding of the mechanism and inner changes of this elite, we focus in 81 families and exhaustively we have tracked down their origin and evolution. The conclusion is that their initial wealth accumulation is linked with a few specific situations. Their economic promotion seems to be related to specific windows of opportunity that open at certain moments and/or places. Once these windows of opportunity close the elites seem to progressively lock on themselves. This tendency created social circles that favored endogamy