The Toome Hill, rising above Old Town, has always been strategic military position. Tartu's original settlement, Tarbatu, was established here in 600AD, and if you trace the hill's outline on a map, you can still see the shape of fortifications built here in the 17th and 18th centuries.
The western part of the hill is clearly dominated by the ruins of the 13th-century cathedral (Toomkirik) that has been decaying since the Livonian War (1558-1583). The sanctuary, which is still in a quite good condition today, accommodates the University’s history museum. Here you can get a broad overview of academic research and teaching in Tartu.
The old observatory of Tartu was constructed in 1811. It was the most modern one in Europe in the 19th century.
References:The Château du Lude is one of the many great châteaux of the Loire Valley in France. Le Lude is the most northerly château of the Loire Valley and one of the last important historic castles in France, still inhabited by the same family for the last 260 years. The château is testimony to four centuries of French architecture, as a stronghold transformed into an elegant house during the Renaissance and the 18th century. The monument is located in the valley of Le Loir. Its gardens have evolved throughout the centuries.