This is a single-arm, single-site pilot of Radium-223 (55 kBq/kg) IV q3 weeks for up to 6 doses in combination with Atezolizumab 1200mg IV once every 3 weeks until investigator determined lack of benefit, unacceptable toxicity, or 17 doses in patients with urothelial carcinoma with bone metastases who have disease progression after platinum-containing chemotherapy.