We have added a Gift Upgrades feature that allows you to gift an account upgrade to another member, just in time for the holiday season. You can see the gift option when going to the Account Upgrades screen, or on any user profile screen.
* Base district cost is now multiplied by the era of the tech or civic required to produce it;
* Costs increase per copy at the rate of 1/6th the new base cost for 1 per city districts, and 1/12th for multiple per city districts (i.e., neighborhoods).
With harbors and commercial districts at 60 + 10 per copy, it was just too easy to spam cities with both, creating 2 trade routes and giving a trade destination that gave +4 production just from those 2 improvements alone. Add that...