Have a Cuba libre -LRB- rum , coke , wedge of lime -RRB- at Old San Juan 's only rooftop restaurant , the Panorama Terrace Bar and Latin Grill at Hotel Milano -LRB- 307 Calle Fortaleza ; 787-729-9050 -RRB- , as the sun goes down and the lights of San Juan and the cruise ships flicker to life .