This was sort of a conference center. It had a bunch of flags, which were given out as awards for the units that were the best prepared or most productive or showed the most Communist spirit. The one of these I can read has something to do with the winner of some sort of farming competition between two of the nearby towns, while others were about the school group that did the best job of preparing for the next year of classes. It's not exactly clear why they took an award for a school group down into a bomb shelter for decoration. Maybe as a depressing reminder that they once had children and farms and stuff.
Even more bizarre, now the conference room of the Ligatne bomb shelter is available for rental for your next party or meeting. Apparently, actual people have held wedding receptions in there. I'm not sure which boggles the mind more: the extreme advanced levels of irony one would need to hold a wedding reception in a bomb shelter decorated with communist propaganda, or the prospect that someone wanted to do that with no ironic intent at all. Further investigation required... but how?