The hills east of Pristina have been mined for silver for hundreds of years and the 13th-century Novo Brdo fortress is a testament to the importance that's long been placed on this region. Much of the fortress was destroyed in an earthquake at the end of the 18th century, but since 2014 an EU team has been busy restoring it (some would say over-restoring it!). Even so, it's an impressive sight and it's fun to ferret around it.
Entry is free but it's likely that a guide will pop out of one of the nearby houses and explain the relevance of the site to you. It's polite to tip them.
There are hourly buses (€2) from Pristina to the small town of Novo Brdo. The journey takes around an hour. From the town it's a short, sharp uphill walk.