Location from A Song of Ice and Fire by George R.R. Martin
Two identical grey castles bridging the Green Fork — the only crossing for hundreds of miles, controlled by the grasping Lord Walder Frey, and forever stained by the blood of the Red Wedding.
The Twins exist because of geography and spite. The Green Fork is too deep and fast to ford for miles in either direction, which means any army marching north or south must either cross here and pay Walder Frey's toll — in gold, marriages, or humiliation — or lose weeks marching around. The old lord built his power entirely on this chokepoint, breeding an enormous family of potential marriage alliances and nursing grievances against every house that ever slighted his dignity. The Red Wedding happened here — the night the Freys violated guest right by slaughtering Robb Stark, his mother, and his bannermen under their own roof. The stain of that betrayal has seeped into the stones. No one trusts a Frey, and the Twins feel like a place where something terrible happened and might happen again.
Two squat, ugly, identical stone castles face each other across the Green Fork of the Trident, connected by a massive stone bridge and a fortified gatehouse at its center. The towers are functional rather than beautiful, bristling with murder holes and arrow slits. The bridge is wide enough for two wagons abreast.
Also known as: the Twins, the Crossing, Frey castle