 Complete the following phrase:  Popp  Asociații had its breakthrough projects in 2004, with the structural design of the Charles de Gaulle Plaza office tower and the seismic structural retrofitting of the 110 year old Bucharest Palace of Justice. The Charles de Gaulle Plaza tower site conditions imposed a top-down infrastructure approach for the buildings 5 underground levels, the first of its kind in Romania. Equivalent ground-breaking techniques had to be used for the Palace of Justice retrofitting and strengthening as the palace was listed in the 1980s to be demolished in 1990 due to irreparable seismic damage following the 