One of the prominent historical landmarks on Martha’s Vineyard is the Gay Head Lighthouse, which has watched over Vineyard Sound since 1856, but whose cliffside location has been endangered in recent years by natural erosion of the coastline. Local townspeople voted, and raised the money, to save the lighthouse, and engineers were brought in to figure out a way to move it, intact, deeper inland. And if expending that much effort for a lighthouse in that area seems excessive, just think of this: The Gay Head Lighthouse is itself a monumental rehab project, having replaced a previous lighthouse that was built in 1799. Check local listings.