The following link filters for "Xcode" in the Apple Developer Center downloads repository:
https://developer.apple.com/download/more/?name=Xcode
This link seems fairly future-proof?
The links have changed since the accepted answer to this question was written; I could not find a link to "Downloads" after clicking "Resources".
Previously, this URL was used:
https://developer.apple.com/downloads/index.action?name=Xcode
