Just North of Narragansett and long in Portage Park, there is short stretch of mound that parallels long Avenue! It only runs about 50-60 feet or So, and is visible as you travel North on Long just before Berteau, right in Portage Park!! Now it is known that a terminal moraine exists on Montrose just North of Narragansett, and runs North and South, and that Glacial retreats are known to have left large boulders from as far North as Canada, and those hills, or mounds, and are quite visible as you travel west on Montrose past Narragansett, but it is natural looking to me at least! But That hill or mound in Portage park is so deliniated, (Pardon bad spelling,) in size and structure, that it seems to be constructed by Man! Knowing that the Pottawatomie Indians lived throughout that North side area, I often wondered if it was a burial ground, and what lies beneath that small stretch of land as well? But because a Native European farmer owned that land for a number of early Chicago years, it just might have been an old garbage trench that built-up over the years! Who knows, maybe you do? I wonder if anyone has information on that particular structure?