Belgorod — a fairly small (~300,000 residents) provincial city with many surviving cathedrals from the turn of the sixteenth century onward as well as a prominent diorama-museum of the Battle of Kursk
Prokhorovka — site of the WWII Battle of Kursk, the largest tank battle in history, and now home to monuments and cathedrals honoring the memory of the many who died
Stary Oskol — the second city of Belgorod Oblast, which has considerably less on offer to the tourist than Belgorod
Les na Vorskle Nature Reserve (Forest on the Vorskla River)
Belgorod Oblast is a relatively unpopulated provincial area of the Russian-Ukrainian borderlands. The city of Belgorod is by no means a major tourist destination, but that in itself might make it more attractive to travelers favoring the less beaten path, and it has a good deal to offer a tourist interested in a more slowly paced, small, provincial capital. The region's biggest attraction, however, is its battlefield legacy as one of the principal stages of the Battle of Kursk, a WWII battle of an extraordinary scale and importance that is one of the principal turning points of the war. Military buffs, relatives of the deceased, and curious travelers will find that, although there is a museum dedicated to the battle in Belgorod, the majority of interesting sites are in and around the northern town of Prokhorovka.
Some knowledge of Russian will be very useful, unless you are traveling with a guide.