D&D 3.0: Tales from Mystara
Thyatis the City is located on the south east corner of the continent of Brun, at the mouth of the Mesonian River. It sits roughly at the midpoint of “Vanya’s Girdle,” the great sound that separates the peninsula of Hattias from the rest of Thyatis. The city’s administrative district includes the surrounding lands (everything within approximately 8 miles of the city falls under the authority of the Eparch). The walled area of the city consists of a rough circle approximately four miles in diameter, plus a small quarter (known as Syclae) just across the river.