How to make an ugly banquet hall pretty??

Could you at least hang Christmas/twinkle lights across the ceiling? What type of theme/vibe are you trying to achieve?

With such a blank canvas, you're in luck! Depending on your overall vision, acquiring items from Dollar Tree or secondhand could go a long way. If it were me, I would concentrate on decorative centerpieces. That way your eyes are drawn to the tables and not the bare walls. Plus once you had tables and chairs it will certainly fill up the space.

I think this could be a really beautiful space depending on the vibe you are going for. Wouldn't take much to turn it into a kind of beer hall wedding if you want something a little more casual and unique.

If you are looking for more upscale solutions, I think having a different lighting option could be key, the flourescent overheads are what take away from the space the most if you ask me. Maybe look into uplighting, or as the PP said, some twinkle lights.

Totally agree! Make people focus on things that you want them to focus on!

I definitely agree that uplighting could be a great solution to change the whole vibe. Also if you just want to do the drape behind the head table wall, that could help as well.

Do up the space like a beer hall with long tables and benches! Could also do chairs, but basically put the focus on the community that came to celebrate with you.

Here's an example photo I found that could work for you, not sure if you could to the hanging garlands since you said you can't put holes in the walls. Maybe with Command hooks?

I think uplighting could be a good way of hiding some of the ugliness without having add drapery. I had a past venue that i was going to hide some of the areas by bringing attention to something else. Remember you will have tables with linen and chairs, centerpieces all to bring out the space so it will come together looking beautiful once its filled.

Lighting like this would be pretty. I would also make the tables and centerpieces look really nice to distract from the rest of the room.

I personally think it'll look just fine when you have all of your decorated tables in there. At least from what I can see, it doesn't look "ugly" IMO. Maybe hang some twinkle lights or paper lanterns. Side note: Where are the bathrooms located? Just making sure you aren't blocking them with your food tables, lol. I can't tell from the layout.