I was so curious about these things when I noticed them at
SM City North EDSA mall that I just had to come up to them to find out what they were. And yes, take pictures. I like how they look, peeling paint and all.
An air conditioner vent at the Sky Dome amphitheater.

This looked like it could have been a WWII bomb or a telescope.

But it's just an exhaust fan in the parking building.