Welcome to the fourth development diary for Europa Universalis 4: El Dorado. Today’s topic is the mythical city of El Dorado itself, or rather the system of land exploration that may just result in your conquistadors finding one of the fabled Seven Cities of Gold. We’ll also be discussing a few other things such as the addition of merchants from Colonial Nations in the expansion and the addition of a large number of DHEs (Dynamic Historical Events) in the free patch.In the first Development Diary for El Dorado we talked about Naval Exploration and how you could send your ships on missions to explore certain sea zones or explore a particular coastline. El Dorado has a similar system for land exploration that we call ‘Hunt for the Seven Cities’.As the name indicates, this system is only available in the New World, and using it is as simple as sending an army led by a conquistador to the Americas and hitting the ‘Hunt for the Seven Cities’ toggle in the unit view. While this toggle is on, the conquistador will automatically explore his surroundings, uncovering terra incognita, fighting natives, and stopping to rest as needed.While a conquistador is exploring in this manner, a large number of events can happen - your conquistador might run out of food, trade with friendly natives, or uncover a lead on where to find one of the Seven Cities of Gold, the Fountain of Youth, or other mythical places that Europeans believed could be found somewhere in the New World. If your intrepid band stumbles upon such a lead, several more events are unlocked as your conquistador follows the clues to an end that can involve failure and death, failing to locate your goal but finding something else of value instead (such as searching for El Dorado but finding Lake Guatavita), or actually locating your objective! You will also be given chances to abandon this quest, should you wish to employ your conquistador in a more traditional manner.Of course, finding the Fountain of Youth won’t actually make you immortal, much like finding El Dorado doesn’t mean you’ll encounter the golden empire of legend. You will find something of great value that will give a permanent boost to tax income, increased trade efficiency, prestige or other such bonuses.Another addition in the El Dorado expansion is a perk for colonial empires that want to bring the riches of the New World back to their home shores. For those with the expansion, every colonial nation of more than ten provinces that an empire has as a subject will give the overlord an extra merchant.Way back in the Wealth of Nations expansion we reworked inland trading. We've further developed that idea by introducing something called ‘Caravan Power’. Caravan Power is a simple addition on the amount of power you gain in an inland node from having a merchant placed there, and is gained from the total tax value of your country up to a maximum of 50. So, a country with 30 total base tax will have +30 power in all inland nodes.The old bonuses to having a merchant present inland and steering towards inland are gone, and have been replaced with bonuses to Caravan Power. This means that a dozen one-province countries with five merchants each can no longer drain away most of the value of Ragusa simply through their combined trade power bonuses.Also part of the free patch is a huge number of Dynamic Historical Events for South- and Mesoamericans, with over 40 events just between the Incas and Aztecs, bringing lots of life and flavor to the New World for everyone.