What is the Friends Tavern?
If you've only started playing, you will notice a ruin along a river to the north of your city. Once you unlock the Brewing research in Bronze Age, this will become a functional building - the Friends Tavern.
Your Tavern will come with its own interior, a small table and a few chairs. All your ingame friends can visit your Tavern and sit at these chairs if they are empty. Whenever there are friends sitting at your Tavern, you will be able to collect Silver and empty the table, making space for new friends to visit you. With this Silver you can activate various powerful boosts for your city or customize your Tavern to not only make it more appealing but also to increase your Silver income.
You can visit the Tavern of every friend once every day. This can easily by done via the social bar - simply open your friends list and you'll find a button for visiting their Tavern (on mobile you will need to tap the player's avatar for this option). To be able to sit down in a Tavern of your new friend, you have to wait 24h for your friendship to become strong enough. To make sure that this limitation does not affect new players, it will only kick in once you have removed 20 people from your friends list.