Wikitravel:Links to Wikipedia
Many of the articles in Wikitravel can benefit from links to Wikipedia articles on the same subject. A Wikitravel article focuses on the issues facing travelers for a destination, but Wikipedia articles can have deeper or broader information on a topic.
To add a link to a Wikipedia article on the same subject, add a link of the form [[WikiPedia:Article title on Wikipedia]]. (Note the capital "P"; it's a long story.)
The link will not appear in the main text of the article page on Wikitravel, but will instead show up automatically in the section "Other sites/languages" in the left-side navigation box.
Add a Wikipedia link to the very end of an article, to keep the article uncluttered. Avoid adding more than one Wikipedia link; the link you add should be to an article on exactly the same topic.
If you need to make a link to Wikipedia for an article that isn't exactly the same, just put a colon in front of the "WikiPedia", like this: [[:WikiPedia:Article title on Wikipedia]]. That will show the link in-line.
In general, try not to use in-line Wikipedia links. The traveler may not be on-line when they read a Wikitravel article, so a link to Wikipedia (or anywhere else) won't be of much use to them. Wikitravel articles should be as complete as possible in and of themselves. Essential information about a topic should be included in the Wikitravel article.
There are many Wikipedias for different languages. Linking to most of them from English-language Wikitravel doesn't make a lot of sense. After all, our target audience are English speakers who won't understand a linked article in Tamil or Estonian.
In addition, don't count on Wikipedia-style interlanguage prefixes to work for links to Wikipedia language versions. We have our own multilanguage sites here at Wikitravel, and fr:Lyon points to the French Wikitravel article about Lyon, not to the French Wikipedia article about Lyon.