This one is not exactly "off the beaten path" located - you will definitely pass the Casa on your stroll through Poschiavo as it is located in the centre and visible even from the major road through the town - but as you cannot go inside and explore, just have a look from outside, I didn't put this tip under the "Things To Do".
The building as you see it was originally built in the 17th century and redesigned in 1856. Architect was Giovanni Sottovia from Vicenza, the same guy who designed the Spanish looking Palazzi in Poschiavo. Anyone will notice the western wing of the Casa that is over and over decorated with frescos. Typical for Poschiavo is the large garden in front of the Casa, quite remarkable its size, especially considering that the location is right in the old town. So the property somehow has the appearance of a Tuscan Villa.
This lovely lake is about 1,5 hours walk from Poschiavo in Le Prese further down the valley. You can hike around the lake in 2 hours. This picture was taken from the southern side of the lake - Miralago.
This part of Poschiavo is a good half hour uphill walk away if you go there directly. The village has a very small old center and a pretty church.
We did actually a loop walk from the Santa Maria church uphill to the right towards a farm, then had a view of La Prese and the lake before turning left to Cologna. Then we walked straight down the main road back to downtown Poschiavo.
This neat little church was open when we arrived, but it was dark inside. We found the light switch though.