Every country has its own secret tombs. These tombs can enter and explore. Sometimes you get the assignment from a local to a tomb to explore such a special relic or something else and look back. Also be advised, because tombs are sometimes full of surprises, and these are not just pleasant!
In tombs found different (secret) passageways. This you need first to open by such a switch stand, a statue on the switch to slide, or a special key in your possession at this door to open. Sometimes you also need a special key to the treasure chests to open. It may seem like an easy chore to these tombs to explore, but sometimes it is surely a moment. Some tombs contained a kind of puzzles. For example a sequence that switches you must activate the door opening.
You can find various treasures in tombs. Sometimes you will find special relics, but good look around, because there are also so-called ‘Ancient’ coins hidden in tombs. These coins can pick up and spend on the market for so-called “Adventures Rewards” which I have already had. To go back out to the market: in each country in a special businessman / woman around. This allows you to your ancient coins handy that special purchase rewards.