It is built on the site of a private mansion, similar to the neighbouring Résidence Palace which was demolished instead of renovated in order to create a much larger modern building. Extra space for the EU institutions were needed in time for the 2004 enlargement of the European Union. At the time, the existing building, Justus Lipsius, could not be extended due to residential areas and the then existing conservation orders on the adjacent Résidence Palace (later partially demolished and renovated to become the Europa building), thus Lex became a new project to satisfy the need for more office space.[1]