Eight United players were among 23 people killed when a plane crashed in the German city on its way back from a European Cup tie at Red Star Belgrade on February 6, 1958.
British billionaire Ratcliffe, the chairman of petrochemicals giant INEOS, is still awaiting the green light for his 25 percent acquisition of the club but he and his team have been a visible presence since the deal was announced on Christmas Eve.
Ratcliffe has visited United on several occasions and was joined at Tuesday's ceremony by INEOS director of sport Dave Brailsford.
The incoming minority owner arrived at the ceremony alongside former manager Alex Ferguson.
Former United players Paddy Crerand and Brian Kidd were in attendance alongside men's manager Erik ten Hag and women's team boss Marc Skinner.
The 66th anniversary came a day after Ratcliffe's deal to take a stake in United edged a step closer.
The billionaire is acquiring 25 percent of the Class B shares held by the Glazer family — which carry 10 times the voting rights of Class A shares — as part of his investment.
Existing shareholders voted at an extraordinary general meeting on Monday to approve a special resolution, under which the Class B shares would not convert to Class A shares when they were transferred to Ratcliffe.
Ratcliffe is also purchasing up to 25 percent of Class A shares and investing $300 million into the club's infrastructure.
The deal is subject to Premier League approval.