Do you need an earth ground, or AC electric ground, or just
a big Faraday shield? Even your concrete floor is an earth
ground - depending on electrical characteristics that were not
provided. Without mentioning frequencies or purpose of the
'ground', then all answers will only be speculation based upon
personal assumptions. What are you trying to accomplish?
Noise reduction? Better signal reception? Human safety? All
may be useful or useless reasons for grounding.

Lucky wrote:
I live on the 23rd floor of a building so I can't use the earth
directly for the ground. The options in my "radio room" are the
ground from the electrical sockets and that's about it.

I've heard I can roll out 10ft of tin foil on the floor as a
ground {that's out}, or, use the window frames as a good ground.
As far as I can tell, the window frame looks to be aluminum or
some sort of alloy.

Have any of you heard of using a window frame as a ground? I think
I read it in this NG that someone recommended it and was using it
for his ground. I've been using the ground from an electrical
outlet.

But being that so many people live in the building that use
appliances and other plugged in items all day and night, I
sometimes get what seems like bad feedback affecting the receiver.

So what do you think of the window frame for the ground then? I
welcome any other options I can use in a room very far from a
direct earth ground. The bathroom pipes are all the way across
the room separated by a wall. Not easy to get to.