A scout ship, looking for new worlds, flies through the sky.  There is one, ahead- teeming with life, something they haven't seen before.  The idea of aliens, even just alien flora and fauna, is exciting enough that they need to view it closer- it doesn't occur to them that there might be actual intelligent aliens on this planet until they start picking up on something on their radio scanner- something that sounds intentional.  Something that sounds like words.  They record as much as they can, trying to find distinct languages and then trying to get some semblance of a computer translation.  They stay far from the planet for several days, and then they approach, sending a radio signal on as many frequencies as they can, first in interplanetary common and then in each of the languages they have clumsily translated.

"Hello.  We are from another planet.  We would like to be friends."

This gets picked up everywhere and then rapidly transcribed and from there rapidly translated into the languages not widely spoken enough to merit radio programs, distributed over teleprinter networks along with a rash of opinions on how everyone should respond.

Ham radio enthusiasts try to answer back first, mostly excited calls without much meaning. The governments are a bit slower, ones with more centralized, smaller bureaucracies in the lead answering first.

"Hello! We would like to be friends, too!" seems to be the near-universal message.

They settle in to orbit, and then send another message to each of the governments they have heard from so far, adjusting their translations based on the responses.

"We would like to come down to visit you.  Where should we land? Is there anything we should do first? Is there any international body we should contact?"

The agreement seems to be that they should definitely talk to the International Science Association, except for these few nations which aren't signatories to the Association and don't really like it.

The International Science Association is very concerned about microbes and thinks they absolutely should not land until they've traded enough biology information to be sure pathogens won't jump across species barriers, or until the Association is sure of the aliens' sterilization procedures.

Most of the small nations who aren't part of the Association think the aliens should land in a specific place in their country.

They are happy to talk to the International Science Association! Here is a bunch of information about their biology, and about diseases common in humans, and descriptions of all the diseases that they routinely vaccinate for (all of the people on board are, of course, fully vaccinated).  Here is a description of their very in depth sterilization procedures for things that they might bring on board, which can be adjusted to be used on them as well. 

Here's some of the same data in return!

The Association believes that full-body self-contained suits and helmets, the exteriors of which are sterilized, will be enough to zero out risk in both directions. And then once they've established what cross-infection risks are - and possibly gotten vaccines for anything that could potentially jump the species barrier in the pipeline - they can start restrictions to various levels of protective equipment.

The crew of the ISS Flora can do sterilized space suits! Where should they land? Who will they be meeting with?  The ships doctor would like to work with their scientists on establishing what the risks are, but the rest don't have the biology knowledge necessary to be of use on that, are there some people interested in talking about cultural differences, giving them a chance to get to know each other?

Fortunately, the time they've spent talking biology has given the international community time to agree on a landing site and diplomatic center - the Eireeya Airfield has room for their ship, and is near the World Sanctuary, where they're hoping to host talks. The World Sanctuary is fully accessible for most of their own people, but they're unsure about the aliens - here are the building requirements, does this work for you?

(The Krissan seem to favor wide hallways and tall ceilings and smooth floors; you could get three large wheelchairs abreast in most of the main hallways, and two in nearly all of the rest.)

It is completely accessible to them! The crew appreciate the concern.  They will land in the Eireeya Airfield, and come out to meet the Krissan.  The ship contains 8 people, who look rather more similar to the Krissan than either group was likely expecting.

That's surprising! Some of the scientists and such in the meeting group mutter excitedly to themselves.

There's ten people present on the Krissan's side, who'll read to the crew of the ISS Flora as half men and half women of a mixture of races and cultures, with no particularly clear indication of a certain uniform among them, though they seem to favor loose, flowing clothes in bright colors, and are mostly wearing skirts and dresses.

"Greetings!" the woman in front calls out. "Welcome to Krisses!"

The crews faces are hard to make out through the space suits, but each suit does have a name tag attached.  

One of the crew members steps forwards.  In direct conversation, his attempt at the local language is much rougher than it was over the radio, where the crew could translate each sentence and get the help of the computer.

"Greetings.  I am Captain Hallos.  This is the ISS Flora and her crew, we are an exploratory vessel seeking new planets."

Another crew member steps forward to stand next to him.

"I am Doctor Ilina, the doctor for the ISS Flora"

"It is my pleasure to meet you." She gestures to one of the men. "This is Marchen, the Director of Medical Research for the International Science Association."

He steps forward, touching his left fist to his right shoulder briefly, mostly turned towards Ilina. "Greetings."

Ilina copies the motion. "Greetings.  Is there anything else you want to get out of the way before we get to work on the biology question? It seems rather more likely that there will be cross-contamination issues now that I see how similar we are, and I would rather be able to get out of this space suit sooner rather than later."

One of the people behind her kicks her leg gently, and says in interplanetary common "Don't complain about space suits to the nice aliens"

"Sorry, I've been on a ship for nearly five years and seem to have forgotten my manners" Ilina says in the language they were using before.

"Is there anything else you want to do before we head to this World Sanctuary? I am curious to see it, it does not sound like the sort of place aliens coming to our worlds would have been taken to."

"Oh, it's alright," Marchen says to Ilina. "And I'd like to work on the biology question right away."

To Hallos: "The World Sanctuary is the sort of place we usually conduct diplomacy. A bit larger scale than we can fill, but it's usually what we use to host large international conventions - so it's the only place people could agree to as a truly representative meeting space for all our peoples."

Ilina will begin asking questions about what they've done so far, and will follow Marchen if he would like to lead her to wherever they will be doing the research.

"Well then, it certainly sounds like a good place to teach us about your worlds cultures.  Shall we head there now, then?"

"Yes. If everyone could follow me - "

Sadly getting into the cars disrupts Marchen and Ilina's conversation a bit. Still, the local team takes care to organize people together by common interests.

The World Sanctuary is massive, it seems, or at least in the middle of a park - their road takes them past a colorful wall,light concrete with stones and glass and shells embedded in it in abstract murals, behind which spread gardens and greenhouses and other buildings. The wall flows smoothly into the entrance itself, a colorful affair, and they park in a covered lot outside of it.

"This is only one of many entrances," she explains. "We try to keep the lots from getting too large. Still, the space has been reserved for our use today. This section covers local history, art, flora, and fauna - I'm unsure of diplomatic customs among your people, but here we try to keep talks from involving too many people at once, and find it's best to spread out serious discussions over the course of a day spent in admiration of nature and art. Traditionally, diplomacy was hosted while hiking, but that's not always accessible, so in the modern day we turned to Sanctuaries."

"This is beautiful.  Our diplomacy tends to take place in government buildings, in conference rooms or offices, not outdoors at all, though I think one of the Venusian countries does huge windows so that you can at least see out into the gardens."  All of the crew look around in wonder, and some wander away slightly too take a closer look at the gardens.

"Thank you. I'd feel awfully cooped up, standing in one place for a talk - still, it's a very reasonable difference for two peoples to have."

"Typically it's done sitting, not standing." He smiles as he says this. "Our oldest settlement, on mars, doesn't actually have any outdoor areas that are livable, it's not naturally habitable by humans and was settled before the development of good terraforming technology.  All of us our descended from the mars settlers, so many of our traditions come from that environment"