Yes, one of the more famous (for it's still-standing huge scale) in southern France called the Pont du Gard. I visited at a younger age and the monument has always stuck with me as defining the words impressive and awesome. This photo is from the perspective of my fourth photo. I have the model on the shelf displayed the other way round, such that the river is on the right. If you examine some other real-life photos, and then the model, you'll note some detailed accuracy (as much allowed for the scale anyway).
Expensive due to my stubborn desire to have certain bricks in the right colours.... some of them turned out incredibly rare, I think I dropped $50 for 11 pieces somewhere along the line there.... Not sure what you mean by how long, so I'll answer in every way I can perceive the question...
It took me about 1.5 months to gather the bricks from roughly 12 or 14 different orders. The total brick count sits at almost exactly 2100 pieces (I'm not sure the exact final count as a couple of unforeseen tweaks had to be made along the way... you can't test structural integrity in LDD unfortunately!). It took me approximately 3 6-hour sessions... I didn't have instructions, so hiding and revealing layers in the digital file ate some time despite all the bricks being pre-sorted (as orders came in). The build in dimensions is 67cm x 10cm x 22cm, or alternatively 84 studs x 12 studs x 24 bricks.