According to the Sims Wiki, "Base camps are a variety of lot and a lot assignment introduced in The Sims 3: World Adventures and The Sims 3: Into the Future.
These lots act as a home for Sims on adventures or visiting the future. There is one base camp in every destination fromWorld Adventures, and each one holds a noticeboard that generates new adventures. The noticeboard also acts a mailbox where sims can submit gems and other items for processing. Explorer NPCs also stay with you at the base camps. Creators using Create a World can set lots to base camp but the lot type serves little purpose in home worlds.
Into the Future's base camp does not include a noticeboard. Instead, Sims take future opportunities from Emit Relevart, the time traveler."
World: China
Name: Shang Simla Base Camp
Size: 64 x 64
Cost: N/A
World: Egypt
Name: Al Simhara Base Camp
Size: 40 x 40
Cost: N/A
World: France
Name: Champs Les Sims Base Camp
Size: 40 x 40
Cost: N/A
World: Oasis Landing
Name: Oasis Landing Community Center
Size: 40 x 60
Cost: N/A
Which is your favorite Base Camp?
