Twin fortresses on opposing headlands, their ballistae and fire-catapults creating a kill zone across the northern sea approach. House Hammren controls both, making them the only merchant-king family with a true chokepoint monopoly rather than mere pilot-guild control. The Hammrens are the closest thing Mueras has to old nobility—they predate the merchant-king system, having held these fortresses since before Kasper's rise.
The fortresses themselves are carved into the cliffsides in the characteristic Mueran style, with harbor facilities at water level and living quarters ascending through the rock. Each fortress maintains a permanent garrison of two hundred, plus the pilot-guild personnel who guide ships through the northern approaches.