i'm down there from 16 feb for a week, so if your there then give me a shout and i'll buy you a pint.

Brecon cathedral, an old benedictine priory (early english) is worth a look in.

Museum: various neolithic/bronze age including a boat.

13 foot regiment museum (Michael Caine "zulu" fame)

Castle: no public access, but it's now a hotel with a bar open to non-residents.

Pen Y Crug hillfort, only 3km or so north of the town

Swlch Tump iron age again just up on a footpath behind the hospital

...it all depends how you're approaching, if you come in on the A40 from Abergavenny there are a series of standing stones along the valley at various points (crickhowel, bwlch, can be seen from the road)

just west of brecon is trallong, the church has ogam stones in it. further on from that into the wilds is Maen Llia standing stone.

burial chamber (what's left) at crickhowell (about 1m from the road) and pennorth (both close to the A40 abergavenny-brecon road).

give me an idea of how much time you've got free and how you're approaching.