Home base and what to do with it

[Schwann145]

Assuming your character and/or party gets access to property of some sort, which type of property would you prefer to have? (ie: anything off the list on pg 127 of the DMG.)

Now, how do you make it, "home base?" As in, what sort of ways do you prepare and defend it? What sort of magical enchantments for offense, defense, utility, or the like do you cast and employ for it? Assume a caster high enough level to cast your desired spells, but otherwise assume RAW/RAI are your options (as in, no homebrew, no special DM fiat, etc.)

[Wizard_Lizard]

A tavern's always fairly classic..

[Zhorn]

I suppose it really comes down tot he type of adventuring group you have.

Chaotic groups that don't abide by the law, but function within a society would aim for their base to be concealed behind a 'front' such as a tavern or shop.

More lawful/renown groups that openly take on jobs as heroes for hire would aim for a openly visible guild hall for work to be directed towards.

Adventurers for fun and glory are in the get rich-quick, live large and fast. To them a Noble estate is the dream to build towards.

Low-key adventurers that operate as a calling may instead have a more secluded and out of the way locale in a hunting lodge, farm, or outpost, close to but not immediately visible from the nearest town/city.

In all such cases, I aim for Mordenkainen's Private Sanctum to lock those places down against divination, teleportation and planar travel, with a nearby hidden location just warded from divination but accessible via teleportation to establish a Teleportation Circle.
Sound warding or a dark and foggy barrier is optional, but mostly reserved for the super secret areas.

Guards and Wards on the doors is also highly desirable, along with a suggestion at a point just before anything important causing those effected to feel like leaving and not delving deeper.

Anything extra is gravy, but the above is my main checklist.

[Kane0]

I'm a sucker for a good fort. Defenses to man, people to manage, resources to gather, fortifications to maintain, plans to make...

What really makes it 'home' is a reason to hang around. Location, location, location!

What I'd do? First thing first, assessment in the war room. How are our resources? How is morale? What are the neighbors up to? Any incidents that need dealing with? What plan are we working on next? This will almost always lead to things to do.

If there is nothing pressing that needs my attention, then I can sink into some 'me' time. Recline in my throne, mingle with the locals, visit the chapel/armory/library/treasury, indulge in some music and art in the gardens and drop by the kitchens before withdrawing to my chambers.

Edit: Improvements are really up to the party members. Artificers can run absolutely wild with anything they can come up with but otherwise it comes down to what tools and ingenuity you have available to you. Casters make a lot of things very easy but that's a double edged sword as they are equally good at dealing with problems. If you have characters proficient in carpentry, masonry, smithing, etc they will have a lot to do.
I usually start with walls and weapons on those walls. After that i'd be looking at some difficult terrain just past those walls and magical improvements and countermeasures as well as removing obvious weaknesses like wooden/thatched buildings, blind spots or a vulnerability to flying threats.

And don't forget to keep the dungeons clean! I don't want any slimes in my soup because the water supply is contaminated by a random ooze that got through the grate.

[Dalinar]

It's slightly adjacent to what you asked, and a lot of it I'm unsure how it relates to RAW, but...

My current campaign is actually largely about fortifying a town right now. We built some walls so there are two main entrances, each one is guarded by an animated golem as well as a couple of player-race NPC guards, and we scout the surrounding forest regularly. We've been at peace for a few sessions, but previously our enemies included flyers that enjoyed firebombing our buildings, so a firefighting plan was a must (we got clean water early on, so nearly every building has at least one bucket of water until our rather self-centered artificer gets around to proper fire hydrants). We have three archery towers (one by each entrance and one at the center of town) and easy access to caltrops to fortify further when we know an attack is coming.

One of the NPCs, a retired artificer himself, had actually built a cannon at one point before we got there, but unfortunately it's busted up now and we don't really have a way to repair it.

My wishlist includes better anti-air, better anti-invisibility, maybe a secret exit or two in case we get sieged, stuff like that. We're in T1, so options are pretty limited. Luckily, this means we probably won't have to deal with stuff like teleportation, creatures with high enough STR to bust through our walls, etc. but these may be concerns for you if your campaign is higher level.

As for spells, the Alarm spell seems like a very useful one at low levels. Arcane Lock, Glyph of Warding. Mordenkainen's Faithful Hound seems like another good choice once you're strong enough to cast it.

[Unoriginal]

It's slightly adjacent to what you asked, and a lot of it I'm unsure how it relates to RAW, but...

My current campaign is actually largely about fortifying a town right now. We built some walls so there are two main entrances, each one is guarded by an animated golem as well as a couple of player-race NPC guards, and we scout the surrounding forest regularly. We've been at peace for a few sessions, but previously our enemies included flyers that enjoyed firebombing our buildings, so a firefighting plan was a must (we got clean water early on, so nearly every building has at least one bucket of water until our rather self-centered artificer gets around to proper fire hydrants). We have three archery towers (one by each entrance and one at the center of town) and easy access to caltrops to fortify further when we know an attack is coming.

One of the NPCs, a retired artificer himself, had actually built a cannon at one point before we got there, but unfortunately it's busted up now and we don't really have a way to repair it.

My wishlist includes better anti-air, better anti-invisibility, maybe a secret exit or two in case we get sieged, stuff like that. We're in T1, so options are pretty limited. Luckily, this means we probably won't have to deal with stuff like teleportation, creatures with high enough STR to bust through our walls, etc. but these may be concerns for you if your campaign is higher level.

As for spells, the Alarm spell seems like a very useful one at low levels. Arcane Lock, Glyph of Warding. Mordenkainen's Faithful Hound seems like another good choice once you're strong enough to cast it.

Two suggestions:

-A patch of well-cared sand around/in the one path to where you want to protect is a great anti-invisibility feature. So long as you have guards who can watch it.

For the fire bombs, I would try curated and waxed leather sheets above the targets, if feasible.

[Kane0]

Leather strip curtains, have to move them to go through even if you're invisible.
If you're feeling magical you can pull the same trick with a waterfall but that's more noisy.

Edit: Have to watch out for *small* critters too, never know what might be a familiar or shrunken/shapeshifted. I'd employ one or more warlocks with the at-will magic sight and darkvision as sentries.