There is something unnerving yet appealing about exploring crypts and vaults. If this seems interesting to you, take a look at Cheonmachong.
When you've spent some time at this Gyeongju tomb site, why not make your way to Hwangnidan-gil Road, Bomun Lake, and Donggung Palace and Wolji Pond? They're not very far from Cheonmachong and also a favorite with tourists.