Wheelhouse

noun

1. A building or other structure containing a (large) wheel, such as the water wheel of a mill.
2. A prehistoric structure from the Iron Age found in Scotland, characteristically including an outer wall within which a circle of stone piers (resembling the spokes of a wheel) form the basis for lintel arches supporting corbelled roofing with a hearth at the hub.
3. (by extension from sense 1.2) A pitch location which is favourable to the hitter.

   "The pitch was right in his wheelhouse, and he hit a grand slam."

4. A person's area of authority or expertise.

   "Horse viruses are in Pat’s wheelhouse."