If only the walls of Castell Aberlleiniog could talk! But seeing they can't, check if tours are available to hear some of its stories instead.
You're spoiled for sightseeing choice when staying in Beaumaris. Castell Aberlleiniog is a great place to begin here, but there are numerous other interesting places to check out. Bangor University, Beaumaris Castle, and Red Wharf Bay are close to the fortified complex and and will cap off your day nicely.