City in the wake of the Yggdrasil: Engineering Considerations

Question

Following on from my previous question about how to consolidate my fantasy setting with science that was successful (thanks everyone!), things have been progressing well in my world design; and my design document is now filled with alot of nice material from local politics to the histories, cultures and religions of the different races

Anyhow, my main initial setting will be Archon's Landing; the capital of the Duchy of Lieve in Everland. This city is built in the wake of the massive Yggdrasil-type tree, The Damaris. The Damaris Tree will be a centrepiece of the campaign, since the interior of it is mostly hollow and somewhat dungeon like (in an Etrian Odyssey fashion).

Since I wanted this place to be interesting to my players rather than just a generic city to get their next quest and sell their loot; I've already started adding more details than usual to this place (as I have done for other major cities in my games in the past), including NPCs.

So, that brings us to our question: what design, engineering and architectural considerations would be important to a city like this? How would it look?

The following conditions have already considered true:

• The tree's circumference is MASSIVE. Even though this city is the capital of one of the greatest nations of the world, it still covers less surface area than the tree it is built next to. We can assume that the tree's diameter is at least 20 miles.
• It is Oak-like. Branches are not feasible to reach for the purposes of construction, and the interior of the tree is not inhabitable. The city is built purely at its base, in its southern wake (so as to not be obscured from the sun as much as possible). The tree does not apparently drop leaves or acorns or anything, and leaves etc. are not giant sized (the tree is apparently more like several epochs old rather than giant-sized in the true sense).
• The city is built to accomodate the tree as much as possible. It has a high/royal district that is built on top of one of the massive roots of the tree. This section overlooks the central city and the northern ward. There are large stairs on the sides of the root, a road that follows the root to the end, and probably a couple of magic elevators. Despite this, people will drill/mine tunnels through shorter parts of the roots if neccessary (this is the case to access the rather dark Deadside, which is a shanty town on the eastern outskirts; possibly overshadowed by low branches?).
• Yes, magic is a thing. Only a small quantity of people can use it proficiently; but it is recognised as a good thing, and mostly not shunned. It's powers are relatively substantial, involving nanomachines that can re-arrange matter, perform rapid thermodynamic alterations, create barriers of force, and access great stores of knowledge. Most mages will only scratch the surface of these powers though.
• Despite the fact that the tree is gigantic; it is only surrounded by regular forest on one side (the east). Most of the other forest has been cleared and the land near the city is fertile and used in regular agriculture.
• A waterfall drops out of the giant tree and forms a small river (The Corkswash) that passes through the city centre. Around 25 miles out from the city, the Corkswash merges with The River Ever, which is massive (Mississippi level). From there, the River Ever carries on about 30 miles to the sea, where there is the port city of Everafter built around its river delta.
• As a result, fishing and foraging for fruit and berries supplement the agriculture.
• There is a large quarry around 50 miles to the north at the base of Mt. Silkenfoot. The stone type here is undecided at the moment. There are also iron, copper, and titanium (ilmenite) mines within reasonable import distances. Titanium processing is possible and not horribly costly in the setting due to alchemy and magery, though those who understand the arcane process are fairly few (most of the cost comes from their service fees, actually).
• Lieve is part of Everland, a Republican Monachy, which has four Duchies (Lieve, Canaan, Tyria, and Nodis) that work in a loose collaboration most of the time. Grand Duke Narron of Lieve is currently in charge, so Archon's Landing is the capital of the entire country, rather than just the Duchy. There was a fairly recent war between Lieve and Canaan over some petty border issue. It was more of a skirmish in the end with only three major battles, though, and Archon's Landing was mostly unaffected, except in the fact that Grand Duke Narron accepted a political marriage to Princess Sasha of Canaan.
• Population of the city is probably around 700K-1 million. Adventurers and tourists by Wyvern (which can be tamed and ridden) probably account for about 0.3-0.6% of those.
• Tech level is, on average, mid-renaissance. Low-tech firearms are available. Due to magic's influence, alchemy, medicine and metallurgy are surprisingly advanced, however.

I guess my concern is would this be designed like a regular old city? At the moment it is, with wealth-segregated areas, craft district, market zone, shanty area et al. The other part is; I've given the ability for people within a few miles to do agriculture. This IS a pseudo magic tree, and it doesn't appear to grow further, so I'm actually proposing it draws nutrients at a reduced rate (only enough for some basic maintainence). Given its size, its probably feasible that the roots go deep enough to hit the mantle. It also doesn't appear to be vulnerable to fire much. Is this too much handwaving or is it concievable?

I've considered Designing a city around a giant tree? and Cities in the trees as data, but none of these precisely address my rather unique scenario!

Answer 1

This is a government center, as well as a primary city. As a primary city, it means it grew organically for trade and defense (against others as well as the elements). I'll try to throw in some design ideas that you might build off of (or dismiss) in addition to what you already have - quarters, districts, etc.

Growing organically, it would center around your river that starts at the waterfall, and goes through the center of the city. This is how trade goods are sent downstream to other cities. So that's your central spine, and you can grow outwards. Two roots of the base of the tree form a V of protection, and the remaining exposed side of town will be walled.

Architecturally, and from an Urban Planning perspective you have to consider two things that have unique impacts on this city.

Classical Vernacular - The colloquial design of institutional & government buildings will no doubt present itself in the colors of the tree, and maybe even the shape of some buildings would resemble the inefficient (spatially) design of a tree.

In the Shade - The Tree will cast a dominant shadow over the city much of the day, but also protect that side from winter winds. Therefore, the buildings might have a slight wedge shape, sloping upward towards the tree: the exposed side facing the tree, protected from the elements. The remainder of the wedge sloping downward away from the tree will protect against winter winds, but include skylights to try to maximize solar exposure.

Answer 2

I think your concerns may be well founded. This city will be fairly similar to most other cities and I don't think there's a whole lot you can do about it. However, it will have a couple of good attributes to it:

• Tourism
  This is a very big tree, the only one of its kind. Anything like that is invariably going to attract people who want to see it. Your city will likely be more tourist-oriented than many others. It's possible that there will be a few companies offering "tours" of the tree where tourists get taken up close and perhaps walk around a walkway that someone has installed on the side of the tree.

• Survivability
  Any part of your city that is anchored to the roots of this tree is going to be very resistant to damage. The roots of this tree are what keep it up, and given a tree that big they have a pretty big job to do. They're going to be very sturdy and capable of keeping buildings up where others might perhaps collapse.

• Adventure
  There are always going to be people who want to know more about this, scientists included. You can expect fairly regular climbing expeditions up this tree to find out what's up there; you might also expect people trying to get inside it without being detected. As new methods are invented of destroying things, they're going to be tried out on the tree: you've invented dynamite? Let's see if we can get into the tree with it.

Other than that, I expect your city would be fairly normal.

Answer 3

The main things that would distinguish such a city would be:

Tourism. A tree this large would attract anyone with the money to see it. It's possible that a whole religion might be built around it, or multiple competing religions. The city surrounding it is enormous, so it is not inconceivable that such a place would be the cultural epicenter of the world, accumulating untold riches. Your wealthy district built on a tree root, or other areas of the city near the tree would attract tourists and the money they bring. This land would be valuable, sort of like expensive beachfront property.

Magic. Depending on the exact nature of magic in your game, there could be an enormous incentive for magic users to come here. Maybe the dew from the tree possesses special properties. Maybe its wood is used in the most valuable elven artwork. Maybe a coven of dangerous creatures has taken up residence in your tree. Making your tree city a center of magic would definitely provide an incentive for adventurers to visit.

Nature. What creatures would live in the wake of such a tree? If we continue your idea of yggdrasil being oak-like and allow for giant acorns, then it makes sense that we would have similarly oversized(and possibly terrifying) herbivores to access this food source. The river could have a similar effect, as it's most likely quite nutrient rich from being filtered down the trees branches. Remember, it would hit the ground at terminal velocity and splash everywhere, possibly rendering a large part of the ground near the tree inaccessible. Later, however, it could be concentrated into one nutrient rich river out of the splash basin. For real life examples of what happens when a civilization grows near an exceptionally fertile river, look to Egypt. Excellent agriculture would lead farmers to establish themselves downstream, and the best plots could be hotly contested. For added fun, create a serious water hazard, like elementals or a cult of aquatic humanoids worshiping Yggdrasil.

Trade. A city like this could export unique products of the ecosystem, minerals found by mining with the aid of hollow roots extending deep into the ground, tea, blankets or tents made from its leaves(are they giant?), magical items(it's gonna be a rich place), druidic paraphernalia, food from farming the river, fish and many others.

Culture and Government. Druids will love this place. The rich will love this place. Anyone with power will come to Yggdrasil and stake their claim. Society could be a magistracy, monarchy or possibly a feudal system where lords exploit the wealth of a limited area by laying claim to sizeable areas of land and the people who live there. Also consider a societal contract with magic users, warriors and lords defending farmers and miners from outside or environmental threats in exchange for wealth. All these systems could conceivably fit within your existing framework.

Answer 4

The Views

In a world where tamed Wyvern are a thing, someone's going to land one on the side of the Tree. That person is going to realize that the view from 15,000 feet is spectacular.

Someone rich is going to build a vacation home there.

Probably, your whole society is structured around "higher is better." It's expensive to haul supplies up the Tree with mid renaissance tech, so only the rich can afford to life on the Tree itself. But the richer you are, the higher you want to live to show off. Maybe 200 or 300 feet is the best people can do at this point, but the ambition to go higher is there.

The Vulnerability

At the same time, the high ground is militarily valuable. If even a small enemy force were to climb the Tree, they could completely bypass the cities defenses. Even without a parachute or glider to get into the city, they could use fire arrows, heated shot, and just plain drop heavy things onto the populace. Also - assassinations.

The Result

Style, even for the ground people, is light and airy. Everyone wants to evoke the feeling of living high on the tree.

Several forts are built around the base of the tree to prevent attackers from scaling it in any kind of numbers. Probably, these become proto-communities. Eventually, many years from now, the city will merge with these communities and completely encircle the base of the Tree.

An additional fort is built as high on the Tree as can be supported. It is manned by the best Wyvern riders in the kingdom, and is the effectively the Praetorian Guard. They always have the high ground.