Here are some pictures tweeted by people on the ground, showing the masses marching to the square, as they get vetted at checkpoints set up to protect the peaceful demonstrators from government-paid thugs: 
Hapa kuna baadhi ya picha zilizotumwa kwa njia ya Twita na watu waliopo kwenye eneo hilo, zinazoonyesha umma unaoandamana kuelekea kwenye viwanja (vya Tahrir), wanavyopekuliwa kwa makini katika vituo vya ukaguzi vilivyowekwa ili kuwalinda waandamanaji wa amani mbali na wahuni waliolipwa na serikali: