There's a beach in South Carolina I go to now and again that has an excellent example of this process. I haven't found a modern fossil in the outcrops, but I'm going to look more closely on future visits. But a perfect example of what I am stressing in this thread.

Even if the majority of all the artifacts created by Homo sapiens is weathered and eroded away, the signs of our activity are etched upon the land, and any visiting alien geologist worth their degree would notice them.

The key, as with all preservation, is to get it buried. That's why I brought up landfills. They are designed to last a very long time and many of them are huge.

We are the first animals that purposely bury the remains of the dead. This greatly enhances the chances of true replacement fossilization.

Volcanic activity will cover some cities and preserve them. (Naples)

Cities built on deltas will subside and be covered in sediment. (New Orleans)

Cities built in rift valleys will be covered in basin fill materials. (Salt Lake)

The Stope and Fill method is used in mines that have narrow, vertically oriented ore bodies. A drift is driven along the ore body. The roof is then caved in a controlled manner (stoping) and the ore moved to the crusher. As the roof gets higher, other material is laid down in the tunnel, which is called fill. This fill consists of rock derived from tunneling through barren rock, concrete, and mine garbage (bottles, cans, lunch wrappers, cigarette butts, napkins, machine parts, tires . . .) As mines reach deeper and deeper levels, they create deposits that are going to last a very, very long time.

How long will the big open pit copper mines in Arizona be around? How about their tailings ponds, some of which cover many square miles? Those deposits will stand out like sore thumb in a stratigraphic column.

Lake Powell will fill with sediment in about a thousand years, at which point the Colorado River will be a big braided stream until it roars over the lip of the dam. What a sight that'll be! Then the errosive power of the falling water will undercut the dam, eventually causing it to fail. That's going to take much longer. Even after that, once the river has returned to the bottom of the pile of sand behind the dam, deposits will be left behind as terraces along the canyon walls and in the side canyons. Careful geologic mapping will tell the tale.

Gotta run, but before I do, I'll leave y'all with a link (Alluvial architecture of the Human-influenced river Rhine, The Netherlands (abstract)) which shows how the very nature of river sedimentation changes under human influence.