The Mugamma reopened for business Thursday morning after a Tahrir Square sit-in prompted the government building to shut its doors for the past four days.
Hundreds of citizens were already pouring into the offices, with many seeking passport and immigration services.
Demonstrators had prevented citizens and employees from accessing the building since Sunday morning to pressure the government to release detained protesters and follow through on democratic demands. The blockage prompted some altercations throughout the week.
Thirteen suspects are being detained pending an ongoing investigation into clashes near the Ettehadiya Presidential Palace on 11 February during protests marking the anniversary of Hosni Mubarak's resignation. Eight others were recently released on bail.
The Heliopolis Public Prosecution has accused the suspects of committing acts of violence, sabotaging public and private property and assaulting security forces guarding the presidential palace