A baying mob of hundreds of xenophobes surrounded the north-eastern city's central hostel housing asylum seekers, refugees and immigrants - applauded by local residents and largely tolerated by police, for three days.
Even once riot police had cleared off most of the rioters, and the refugees were taken to safety, neo-Nazis returned and set fire to a neighbouring hostel housing around 150 Vietnamese workers.
Although they managed to escape without serious injury, the long weekend in Lichtenhagen in 1992, soon after German reunification, seemed to show a deep-rooted and widespread racism in the east and became known as the shame of new Germany.
President Joachim Gauck, a Rostock native, was there at the weekend, and called for resistance to racism.
"We are not going to give in to our fear of the extreme right; we will not allow that,” he told Saturday's Ostsee Zeitung newspaper.
The president said the demonstration was taking place "to show that we in Germany really do have a culture of defending against extremism and that we want that to remain the case."
Organisers said up to 6,000 people had showed up to the event, marching through the city to the “Sunflower House” – site of the original riots.
Under the motto “20 years after the pogroms - the problem is racism”, they wanted to highlight the spread of racism to mainstream society and media, as well as calling for changes to the asylum laws.
“We are also here to remember those who at the time did not call the fire brigade,” one speaker said, referring to the lack of action from residents at the time.
They also mounted a memorial plaque at the city hall. It was a replica of one that a French-German-Jewish group led by Nazi hunter and former challenger for the presidency to Gauck, Beate Klarsfeld had taken to the city hall shortly after the riot in 1992. The original group was detained and the plaque was removed and subsequently lost.
Further events were planned for Sunday.
The anniversary also prompted further calls for the banning of neo-Nazi party the NPD - although a previous attempt failed because too many of the top party functionaries turned out to be in the pay of the authorities, contaminating their evidence.