There's not. The only way to get there is to climb those ladders on the outside that I circled in orange, and then follow that path I drew with the arrows INSIDE the building (you can't see the opening from there, though you CAN see the opening where the bird comes out). At least, I am 99% sure that how you get there.
View attachment 55594
Edit: Or maybe you follow those stairs along the left edge and enter through that opening and THEN walk around inside...I can't remember now. Either way, it's ONE of those two ways for sure.