We report a case of adenocarcinoma of the urachus showing extensive calcification and stromal osseous metaplasia, arising in the bladder dome of a 51-years-old man. The patient underwent partial cystectomy, including in block excision of the entire urachus and umbilicus, and remains well, free from symptoms after a 22-month follow-up period. Main pathologic and clinical characteristics of urachal calcified tumors are reviewed. To our knowledge, this is the first report in the English literature on urachal carcinoma showing both extensive scattered calcification and massive stromal osseous metaplasia.