How to find my Subversion server version number?

To find the version of the subversion REPOSITORY you can:

Look to the repository on the web and on the bottom of the page it will say something like:
"Powered by Subversion version 1.5.2 (r32768)."
From the command line: <insert curl, grep oneliner here>

If not displayed, view source of the page

<svn version="1.6.13 (r1002816)" href="http://subversion.tigris.org/">

Now for the subversion CLIENT:

svn --version

will suffice

Let's merge these responses:

For REPOSITORY / SERVER (the original question):

From an earlier answer by Manuel, run the following on the SVN server:
```
svnadmin --version
```

See the "powered by Subversion" line when accessing the server via a browser.
Access the repository via browser and then look for the version string embedded in the HTML source. From earlier answers by elviejo and jaredjacobs. Similarly, from ??, use your browser's developer tools (usually Ctrl + Shift + I) to read the full response. This is also the easiest (non-automated) way to deal with certificates and authorization - your browser does it for you.

Check the response tags (these are not shown in the HTML source), from an earlier answer by Christopher

wget -S --spider 'http://svn.server.net/svn/repository' 2>&1 |
sed -n '/SVN/s/.*\(SVN[0-9\/\.]*\).*/\1/p'

From an earlier answer by Milen

svnserve --version   (run on svn server)

    Check out the current version in a FAQ: 
    http://code.google.com/p/support/wiki/SubversionFAQ#What_version_of_Subversion_do_you_use?

TBD

Please edit to finish this answer

svn --version