I came across this site in one of my educational technology sites:
The site claims: "SecretBuilders is a site that can be used to supplement the teaching of various topics, including literature, arts, sciences and humanities. The site gives children an opportunity to interact with famous historical and fictional figures from world civilization, making learning more enjoyable and effective. We can provide teachers with examples of how to incorporate SecretBuilders into their school curriculum."
Take a look and see what you think.