I want to award property and land as a reward for a set of adventures. I'm creating a campaign in 5th Edition, and I want to follow the treasure per level guidelines. I know I can measure the building's value, but what about the land it is on? Is there any source material that would include land itself?
I wouldn’t worry much about the value of any property that you give your players. In 5e, wealth by level isn’t assumed in the balance of the game and the lack of a magic item economy makes it very hard to unbalance the game by giving you players too much money.
In a medieval setting, the value of property is going to come from a mix of strategic concerns and income it produces. Strategic value really just gives your players more opportunities for roleplaying and it is as likely to cost money (we need to hire guards to protect this trade road now) than to generate it. Income, as Garret Gang mentioned in his comment, is basically completely under the DM’s control. Are you worried that your players’ farm is giving them too much money? Bandit attack during the harvest! Now you’ve limited their income and given them a new quest, one that they’re likely to be highly invested in.
Basically, my opinion is that you can’t go wrong with giving your players property. It makes them more invested in the game world, generates limitless quest and roleplaying opportunities, and is just likely to be a treasure sink (but one that they enjoy putting money into) as a source of income.
I realize that doesn’t strictly answer your question. If you’re concerned about limited treasure, would value property on the net monthly income it generates.