Eighteen red brick buildings sit abandoned on Boston Harbor’s Long Island. They’re the ghostly remnants of what looks like a small college campus. It’s where thousands of people experiencing addiction or homelessness were treated and sheltered for many decades. According to the Boston Public Health Commission, the island was first used to shelter people who were homeless in the 19th Century. At some point the shelter went dormant. The bridge to the island opened in 1951, and the city opened its most recent homeless shelter there in 1983. Many addiction treatment programs ran on the island over the years.