Kind of a weird question for you dog experts out there

I have my three-year-old German shepherd by my side on walks every night. She exhibits as normal behavior as any dog would in any type of situation. Nothing particularly abnormal about her general personality at all, but she does something that kind of interest me and freaks me out at the same time.

When we walk together, day or night, we'll usually go down the same path in my neighborhood. Walk past the same houses, through the same parking lots, and the same fields. However during our walk we'll always usually cut through a small parking lot for a bank. When we've reached the end of it, there is a square section of sidewalk that connects the two buildings between the bank. My dog will go nowhere near it. She always drags me along to the edge of the sidewalk, but never walks directly through it, even when I try to force her. I can't understand why. There's no weird smell and it looks exactly like all of the sidewalk around it. There's absolutely nothing there, and she acts like she's seeing something she's truly afraid of.

Any ideas as to what is going on?