When in Providence Lovecraft greatly enjoyed visiting nearby Newport, although the trip involved a long and sometimes chilly boat trip. One of the attractions of the place was its antiquities and perhaps its many grand mansions. Including a monstrous castle which could have come straight from one of Lovecraft’s tales…

The vast structure was however wryly called a “Cottage” by the inhabitants of this isolated shoreline castle. It was demolished in 1924, but Joshi has Lovecraft visiting Newport as early as 1915. He also went to Newport with Sonia just prior to the New York years, which gave rise to the joint tale “The Horror at Martin’s Beach”. The above mansion was still there at that time. In the tale such structures offer a key setting…

It was in the twilight, when grey sea-birds hovered low near the shore and a rising moon began to make a glittering path across the waters. The scene is important to remember, for every impression counts. On the beach were several strollers and a few late bathers; stragglers from the distant cottage colony that rose modestly on a green hill to the north, or from the adjacent cliff-perched [Wavecrest] Inn whose imposing towers proclaimed its allegiance to wealth and grandeur.

Now, Lovecraft’s “Inn” is hardly rustic, since it is described as having an ornate balcony and a “sumptuous ballroom” inside. It operates as a very upmarket “hotel”. The setting is then similar to that of the mansion on the postcard. More so when one knows that this real-world monstrous “Cottage” castle was apparently adjacent across the water to a far more alluring “cottage colony” of writers, as in the story. The name is also similar, the mansion being dubbed ‘Breakwater’ in reality, and ‘Wavecrest’ in the tale. All this suggests that the postcard shows the setting of a Lovecraft tale, albeit a joint tale.

There are two illustrated books on the topic, free on Archive.org, A Guidebook to Newport Mansions and Newport mansions: the Gilded Age, each giving views inside such structures as survived into the 1980s.