A convoy of more than 100 cars and bikes marked the 46th anniversary of the Birmingham pub bombings.
Friends and relatives of the 21 killed and 220 injured in the 1974 atrocity began in Aston and were ending at West Midlands Police's headquarters.
Campaigners are calling for a public inquiry to establish "truth, justice and accountability".
A 65-year-old man arrested over the bombings on Wednesday in Belfast was released on Friday after questioning.
The man, reported to be 65-year-old Michael Patrick Reilly, was held under Section 41 of the Terrorism Act 2000 and has strongly denied any involvement in the bombings.
Six men - Hugh Callaghan, Paddy Hill, Gerard Hunter, Richard McIlkenny, William Power and John Walker - were wrongly jailed for life in 1975 for the attack.
Last month, Home Secretary Priti Patel gave campaigners fresh hope by considering the case for a public inquiry, saying she "recognised the desire to see those responsible brought to justice".
"If we don't have hope, there's no point in us campaigning. We might as well give up," said Julie Hambleton, whose sister Maxine died in the bombings.
"But we will never give up, we will never go away until justice is seen to be done."
Inquests last year found an IRA warning call was "inadequate" for the purposes of ensuring that lives were not lost in the explosions.
The call, made to the Birmingham Post and Mail at 20:11, gave the bomb locations as the Rotunda building and the nearby Tax Office in New Street but made no mention of pubs, costing the police vital minutes.
The first bomb detonated in the Mulberry Bush seven minutes later, and the second exploded in the nearby Tavern in the Town shortly after.
A third bomb was planted near Barclays Bank on Hagley Road but failed to properly detonate.