January 2023 this is possibly one of the least exciting WHS to visit. Anyway WHS lunatics want to tick it off the bucket list. On our Baltic Trip 2017 I completely blanked out the two spots around Vilnius. Years later I was still mad about. Now, on a spontaneous trip to Tallinn and surrounding my travel buddy asked me, whether visiting Tartu would be within our itinerary.
Of course! I am happy to visit! So after daytrips to Helsinki and Laheema NP in our 4th travel day we took an early train to Tartu through wonderful snowy Landscape and arrived approx. 2 hours later.
Tartu will be European Cultural Capital in 2024, so there is a bit more to visit than just the observatory. On Sundays it's closed unfortunately, but I guess you get to see more than at some other measuring points. The view above Tartu is also lovely.
Tartus old City alone is worth a daytrip from Tallin. We enjoyed this sleepy and charming town.