I want my renders to show up any time someone types "Tenochtitlan" into a Google Image search. I thought Flickr might be the answer, but I can't even get my tagged images to show in their own search engine. 

Renderosity is most certainly not the answer, of course. You have to be a member to view.  

After several months and endless hours of often frustrating labor I'm just not satisfied with fifty views tops and the lasting isolation in this CG red-light district.  

try creating a web page and hope googlebot and such finds you?

wordpress websites are generally pretty good at getting crawl stats on google etc,

easy to set up, and free if you dont mind having .wordpress.com in your url.

tons of free "themes" on the web too.

Also try get it on e-on with the pic of the day, cornucopia, mtvs new art thing (the name eludes me), flickr, all those sort of things :)

Or get your own dot.com? :)
I've had one for about 10 years, iirc., currently just pay the costs of regeistering every few years, plus £10/quarter, unlimited size, UK only though

Attached Link: Web hosting

Whatever you do.  Don't spend money to be on a list.  Google will find you if you're on a blog site or web site.  Use the seach name as the JPG filename and you are on everyone's web and image search engines.

It takes three weeks for Google to search the entire Internet and find or update your presence.

"It takes three weeks for Google to search the entire Internet and find or update your presence."

crikey... really?  fast lil botty!!!

Quote - Renderosity is most certainly not the answer, of course. You have to be a member to view.  

Renderosity has managed to get tens of thousands of pages indexed in Google, including some news and image pages, probably by using cloaking based on user agent.

But the question is: do they get ranked?

I post my images on several different websites: my own one (www.virtual-lands-3d.com), Elfwood, Renderosity, DeviantArt and Epilogue. I made a series of tests in Google Images for some keywords contained in my image titles. : only my website and elfwood rank on keywords in image names such as Gauntlgrym, Tantrevalles, Ledo road and elven fortress.

So what does this mean?

If you cannot post on Elfwood, the surest solution is to make your own website, focused on Tenochtitlan or Aztec imagery.
You will be able to optimize it the way you want. The main problem will be getting quality  inbound links and gain enough popularity to rank. It took 6+months for my website to rank on interesting queries for instance.
I think you should also make sure the website is designed to achieve well defined goals. Getting trafic is one thing, transforming it is another. Maybe you could come up with more specific queries containing the Tenochtitlan keyword.

Sorry for the lenghty and OT answer but I could not resist (I am a SEO Consultant in "real" life).

Having several Wiki sites linked to your site doesn't hurt either.  Google tears through Wiki daily for new links to add.

Once you are on Google's first page of hits, you may notice that some days you are number 1, some days number 6.  Google rotates which site gets listed first.  If you pay them money, Google will throw your site up at number 0 and keep it there until your run out of money.  Most people are happy with being on the front page in the top 7.  Casual Internet people don't browse past the 7th link on Google.

Quote - Casual Internet people don't browse past the 7th link on Google.

Recent analysis of the click through rates on the first result page of google show 60 to 80% of the users click on the first three results, leaving very little for others. Of course, this depends on context, but it is quite interesting. The study is available here: http://www.seo-scientist.com/google-ranking-ctr-click-distribution-over-serps.html The situation is probably quite different in images search engines.

unless I'm after specific information, I rarely go past the third PAGE (i'm stubborn LOL)... but have been known to go to about page 50 on some things, JUST to find that bit of info.

Interesting how the search engines rank things...

Become a member of ArtSpan and create your own web page.
or, Create a Web Site and set up an XML index with a search page.  Google will find you quick.
or, Enter a well known Art Competition and win.  Like www.upstreampeoplegallery.com again, the search engines will find you.  After I won I got three offers from Galleries to represent.

If you have a Web Site or Web Page you can link to other sites and help step up your traffic.  It takes a lot of work and you want to go with those sites that get a lot of traffic and have good rankings in the search engine.

It took me more than a year to get a top rank in the search engines and now I have traffic at my sites in the thousands each week.   I also advertise in Google Adwords and Microsofts similar advertising scheme.  it dosen't happen overnight.