This memorial celebrates the first translation on 24 May 1233, of the remains of St. Dominic, who had been buried in the church of St. Nicholas of the Vineyards at Bologna and where many people had been healed. This marked the beginning of the canonization process, which culminated with Pope Gregory IX’s decree in 1234.
Poor St. Dominic wished to be buried simply. However he was placed in a marble sepulchre. The tomb was added to and added to. It is now known as the Ark of St. Dominic.
Since St. Dominic always did God's will. He would have acquiesced to the will of God. St. Dominic really doesn't care where his remains lie, but we can now pilgrimage, and make homage to this great man of God.
h/t: above video is of Dominican friars pilgrimaging on the day of the Translation of St. Dominic.