The Tula Kremlin is the oldest surviving structure in the city, built in the early 16th century as a stone fortress to protect Moscow's southern approaches from Tatar raiders. It is smaller and less famous than its Moscow counterpart, but in some ways more approachable — you can walk the full circuit of its towers in under an hour.
The kremlin was comprehensively restored in the 2010s and now looks crisp and well-maintained. Inside the walls sit two cathedrals: the Assumption Cathedral, built in the 18th century in the Russian Baroque style, and the older Epiphany Cathedral. The surrounding park and embankment along the Upa River have also been renovated, and on weekends the whole area fills with families and food stalls selling Tula pryaniki (spiced honey cakes) and samovars' worth of tea.