[@Kazemitsu]
The Frrgotten Ruins are a city, based solely on the surface of the grasslands. If there were underground sections like sewers or tunnels, they have long since collapsed or flooded over with centuries of rain, hail and snow. There are only buildings on surface-level left now.

[@Click This]
No nation uses copper coins.
Silver is the lowest kind of currency.
As there is no [i]universal[/i] currency, the exchange rate of silver-to-gold varies depending on nation.
As such, I can only tell you the exchange rate for Palagria at this time, since it's the only nation I've (officially) created and listed so far.
In Palagria, silver is typiaclly exchanged at a rate of 1,000 to 1. Ergo, a thousand silver coins equals one single gold coin in Palagria.
For a feel for how prices work for mundane things, regular food items in Palagria usually sell for between 1 to 12 silver, depending on how hard the item in question is to get/make.
Luxury foods or drinks tend to be sold at - usually - 20~100 silver, again depending on the rarity and difficulty of making/acquiring.

Basic food would be stuff like potatoes, tomatoes, carrots, sack o' grain, loaf o' bread, etc.
Luxury foods would be stuff like chocolate, honey, coffee, tea leaves, wild game meats, pastries, etc.

I hope this helps. If you need further explanations or examples, let me know.

[b]EDIT:[/b]

Note: If there is a shortage of something, prices obviously rise.