For an unique history lesson, visit the crumbling remains of Knights of the Sword Castle and try to imagine how it must have looked in its glory days.
You'll be spoiled for sightseeing choice when spending time in Sigulda. Knights of the Sword Castle is an ideal place to kick off here, but there are loads of other worthwhile places to explore. Gauja National Park, Turaida Castle, and Sigulda Castle are near the once-important structure and will round out your day nicely.