Coin Talk

If you were given a 5 pound bar of pure gold and were allowed ONE leap back to 1 specific place and date in time to spend 8 hours there. Then you have to return to your real time with whatever you are able to carry in a single backpack.
To what place/date would you leap ?
What investments would you make (if any) while you are in the past ?
What would you bring back with you ?