I can't seem to find anything online about it, but, here on the island of Martha's Vineyard (off Massachusetts), there is a small stone structure in the town of Chilmark. This has always been attributed to Viking construction. It's basically three stone slab walls with a roof. I saw it a few years ago while plumbing a house on the plot of land it's on. Only a few amateur archeological digs have been done at the site as far as I know.