This show was all full of South Africans, but I saw it in the mid/late nineties on YTV, really reaaaallly late at night. It was called "Legend of the Hidden City" or "Hidden City" (the Internets do not agree), and it had four archaeology students accidentally finding a city full of period (I think) Mayans... possibly...? Does anybody else remember this or know if it's on DVD?

Secondly, an Aussie brother and sister fall through a magical portal into Imperial China, and at some point the sister is zapped into another dimension where a whole lot of French people (read: powdered wigs, corsets and crinolines) have taken a youth serum and therefore can't have babies, so they try to feed it to her so she'll be a child forever and can be loaned to each couple in turn.

I did not imagine these shows. It's like Ocean Girl. They've just vanished. :(