Sigulda - the Switzerland of Latvia. Friend Geoff says that whenever anything is described as "The ______ of Latvia," one should prepare for disappointment. In Sigulda's case, this is a little unfair. It's pretty nice. Sigulda gets the name from its not-uniformly-flat terrain and its castles. Of course, what the tourism bureau wants you to know about is its various 'adventure' attractions - bungee jumping, bobsledding, an arboreal obstacle course called 'Tarzans'.
The castles are quite an eclectic mix. The run the gamut from tumbledown Dark Ages ruin to baroque summer home converted to a swanky restaurant. I spent the most time at Turaida, a castle that was steadily expanded from its foundation in the 13th century until its destruction in the 18th. It has been reconstructed as a park and museum, though its shiny new bricks (bricks!) do lessen the sense of verisimilitude. The park includes traditional Latvian statuary, lovely gardens, and a memorial to the Rose of Turaida, a legendary woman who died to preserve her honour. The memorial is now a destination for newlyweds to pledge their love. All good castles should have local lore like that.
Sigulda also hosts a charming river valley hike, occasionally broken up by the need to follow a main road for a time. Along the walk is Gutmanis Cave, the largest cave in the Baltic states (about 20 feet deep), which is much more interesting for its engravings from visitors - going back centuries. The cave is also the site of the death of the Rose of Turaida.
Recommendations: a nice spot for hiking and sightseeing. Well worth the hour train ride out of Riga (though do check the schedules or you'll end up waiting at the train station forever like I did). Don't go bobsledding.