Locked my bike to a regular inverted U rack that I often do, but didn't double check it like usual, because there was a family getting out of a van parked next to me. Went upstairs to my friend's apartment, came back down three hours later and it was gone. There was a puddle of water at the base of the post it was locked to that wasn't there before. The rack was still firmly attached to the pavement. I staggered up and down the busy street for a while in disbelief, battling tears, then pulled myself together a bit. Unfortunately neither the business it was directly in front of nor the business across the street have clear sight lines to the rack, as I found out when I went in to check, though the travel agent at Costa Azul said he didn't think he had seen a bike when he got in at 10:30. In short, I don't know how the bike was stolen in the middle of an active street, though I'm pretty sure I secured it.