The Come Visit My Dungeon sticker is a bit of early TSR ephemera that I have written about once before, way back in 2012. It was brought to my attention again recently when Ernie Gygax joined Twitter and pinned a post with the above photo, which is the highest resolution version of it that I have seen. The writing on the sign to the right is visible as:
"Lasciate ogni speranza Voi Ch'Entrate"
Which is from Dante's Divine Comedy, and is well known in translation as:
"All hope abandon, ye who enter in!"
The sticker art appears to be unsigned, and I haven't heard anywhere else who the artist is; I'll update this post if I learn this.
The sticker is associated with the Dungeon Hobby Shop. Per Ernie: "We had stacks of [this sticker] in our Shipping Dept of the Dungeon Distributors. I do not remember why we had them though. I think it is from the 772 Main St days rather than the earlier 723 Williams St." Elsewhere, Ernie indicated that the sticker was given out with purchases of a D&D set.
However, the sticker may date back further than that, as TSR moved to 772 Main Street in the later '70s; the earliest date I've found in Dragon for that address is in The Dragon #20, November 1978. But there are several examples of the sticker attached to an early "woodgrain" OD&D set. One example can be seen in my earlier post, and was owned by Dave Arneson himself; it also has an address label with his name on the cover. Reportedly, he didn't care for the art on the cover. On the Acaeum, another copy was said to have had the sticker placed inside the box lid by Gary Gygax when bought from his basement. There is also a roughly contemporary TSR T-shirt with the same Come Visit My Dungeon slogan on the front, under the art also used on the cover of the first issue of The Dragon. The back features Greg Bell's Lizardman art from the inside cover of Greyhawk, also used as TSR's "Lizard Logo". You can see a great photo of this T-shirt here, and another of Rob Kuntz wearing it here.