Simco's is a classic hot dog stand located just north of Mattapan Square and the Milton border (there is also a second one in Roslindale) that has been around since the Great Depression. You can't miss the well-worn signs that are on the front and the side of Simco's; indeed, these signs look as if they are the original ones from the 1930s. In fact, everything about Simco's seems to be from another era--the simple displays in the windows advertising every kind of food from pizza to spaghetti to chicken to fish to ice cream. But for those who are regulars at Simco's, the hot dogs perhaps rule over all the other dishes. Not quite foot-longs, Simco's hot dogs are thin, juicy wieners with a barely noticeable skin (a good thing for those of you who are turned off by natural casings). And they can be ordered as a cheese dog or a chili dog, or both, any of which are well worth getting. The buns are buttered and grilled, rounding out this bit of culinary perfection.
Simco's is a true slice of Americana; the young and old alike come here day in and day out, trying to grab the parking spots out front or over by the adjacent railroad bridge, while on Sundays, neighborhood folks pour out of the church across the street in their Sunday best, ignoring the potential for chili- or cheese-related disasters that can (and will) develop while eating Simco's dogs. And on warm summer nights, diners can be seen sitting on stoops or along the bridge, enjoying some of the best hot dogs that Boston has to offer. If you haven't been to Simco's, get over to Blue Hill Avenue and check out this memorable hot dog
Source: Boston’s Hidden Restaurants