From what I gather the Euro has been a long time in the making. The site below gives the objective in three stages:
The successful development of the euro is central to the realisation of a Europe in which people, services, capital and goods can move freely.
Ref. https://www.euro.ecb.int/en/what/history.html
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A currency is a pillar of national sovereignty; for the EU to centralise Europe into a single entity it must remove this and other pillars of national sovereignty from each country. This is done through the Euro and the concomitant obligations (such as countries transferring their gold reserves to the EU (Frankfurt)).
You may be able to find more info from some of the links at:
https://www.euro-know.org/
Dubhdara
International Level: Junior Politician / Political Participation: 100 10%