Is time circular

For periods in human history our world, the Earth, was believed to be flat, beginning somewhere and ending somewhere else. No one could believe that by going west, for example, for long enough, would have you back to where you started from if you kept going for a finite amount of time in the same direction.

Is our perception of Time similarly flawed? Is Time circular rather than linear? Are the incredible stone monuments we see, in Egypt, for example, our own constructs from sometime in the future created as a warning message to us here, now, using the technology currently at our command?

Or, were they created by an ancient advanced civilization that disappeared without any other traces way back in antiquity on the linear timeline inside our heads?

Just askin’ : )