The Covenant

"Mons Obscurus, the best of covenants, is located in Saropshire, Western England, near the Welsh border. It occupies a a wonderous regio which encompasses, layer by layer, an entire mountain which provides plenty of everything that human beings need.
Every kind of common material is found thereon in great abundance, and it has broad fields and hillsides covered in rich soil, which can produce every kind of crop in their seasons, for the weather is always that due for the season, and utterly predictable in form and extent. 
The magi do dwell in towers of stone which, elevated by their stony foundation, do pierce the sky with their spires while clustered all about are the dwellings of their covenfolk who work industriously upon the land and its bounties to produce assorted goods and tend to the needs of the covenant.
There are open woodlands, and nearby lies Hockestow Forest which is filled with every kind of game. The forest glades provide pasture for cattle and the fae make garlands from the many-coloured flowers from which bees take honey. 
The windswept mountaintop rises majestically over expanses of vividly purple heather and tufts of the greenest grass, beautiful places where clear springs flows into shining streams which lull those lying on their banks into deep and untroubled slumber.
What is more, it is filled with deep, water-filled caverns where ancient beings do stir, ornamented here and there with the works of ancestors who wrought their monuments in enduring stone and hard-packed earth, and basks beneath the bluest of skies in which the spirits of the wind itself do wrestle with the clouds and stars do gather in a greater host than in any other night sky I have gazed upon."
From an address by Marco, a Redcap fond of wild tales and large women, given before an assembly of his peers at the Mercere House near Coventry, England in the Year of our Lord 1221.
"The covenant is the single most important character in most Ars Magica sagas, because it is the character that all players contribute to. It is their home, a secure base, and the place where they study, improve, and create magical wonders. Thus, coming up with the concept for the covenant is very important, as it will have a strong influence on the feel of the saga."
Page 69, Covenants, Ars Magica 5th Edition