During the rule of Augusto Pinochet in Chile, sporting arenas were commonly used as mass jails or torture centers or interrogation or execution sites. That's not a unique thing; stadiums are surprisingly useful for such purposes if you happen to be a dictator. You know how many thousands of people you can cram into the place, a lot of places to hide things in the bowels of the stadium, a big open field to use for whatever, you control all the entrances and exits, and you can hold sports and political rallies there once you hide everything from everyone who doesn't need to see that stuff.
One such stadium, Victor Tara in Santiago, was one of them, put into action immediately after the 1973 coup. But that time is over now, and winter is here in the Southern Hemisphere. And stadiums can be used for other things too.
Like homeless shelters.