Lightspeed - S5-E8
Revealing mistake: When the HIVE Five exit the museum and are intercepted by Kid Flash, Mammoth loses both his pants and the artifacts he has before KF whizzes past him. It's best seen in slow motion; at normal speed this mistake is hard to catch.
Chosen answer: It is located in California, as shown in "Teen Titans: Trouble in Tokyo". Possibly San Francisco as seen in the comics.
MasterOfAll