Resources

Antiquity Site

These special sites are not revealed on the map until your civilization has discovered Archaeology. After that point, these sites appear throughout the world. Your normal Workers can't do anything with them; instead, you need to train Archaeologists. Do so, and then send the Archaeologists over to the Antiquity Sites. They'll create an Archaeological Dig. When finished, this grants your nation an Artifact, or you can turn the site into a Landmark if you're borders cover the territory and you want to get Culture from that area.

Archaeologists are consumed when they build their dig sites, so you have to create one for each Antiquity Site that you find. Make sure to hurry because other nations are going to be interested in gathering these for themselves. Artifacts help with securing a Cultural Victory, while Landmarks are better for protecting your society from someone else's Tourism.

Hidden Antiquity Site

Functionally, these sites are identical to regular Antiquity Sites. The only difference is that this variety does not appear on the map unless your nation has finished taking all Policies from the Exploration Branch. It's a nice reward for something that most naval powers were going to do anyway.