The gatherings today came in response to calls by Islamist parties and other political forces aligned to the Muslim Brotherhood after days of anti-Mursi protests rocked the country.
Many of the supporters who assembled here today were carried by buses from the Delta governorates.
Protesters displayed posters and banners supporting the president's recent decision to grant himself broad powers as they gathered in the show of support for 'legitimacy and Sharia'.
'The Muslim Brotherhood supports the decisions of the President', 'The people support the decisions of the president', were some banners held by the people.
Demonstrators chanted, 'Islamist (state) everywhere', 'Islamist (state), against injustice and tyranny', and 'God is great, people (support) the decisions of the president'.
Outside the Cairo University, demonstrators set up a platform, while groups of young people acting as security and wearing neon vests fanned out around the edges of the demonstration to protect participants and direct traffic.
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The pro-Mursi protests were originally to be held in Tahrir Square, but the Brotherhood organisers changed the location to avoid a confrontation with the Mursi opponents who were camping at the iconic protest spot.
Tens of thousands of anti-Mursi protesters had marched to Tahrir yesterday, calling for the dissolution of the Islamist-dominated Constituent Assembly that approved a draft constitution based on Islamic law, as they chanted slogans against "dictatorial Mursi".