I believe much of the Ancient writing that we see in Atlantis (and possibly in Stargate once the Atlantis series began running concurrently) can be translated to english.  To make the translations we have the ancient to english dictionary (source: [stargate wiki)][1]:

[![Ancient to English translator][2]][2]


#Atlantic Gateroom Stairs#

(Note: the writing on the main stairs translates to English, but the ancient writing on the stairs up to the platform the gate is on doesn't seem to translate to meaningful English sentences.)

[![Atlantis Gateroom][3]][3]

> We hold these as the truth
> 
> A hearty welcome to those of other worlds
> 
> Visiting our home for the first time welcome again
> 
> To those returning you have been gone too long and your
>
> Absence has weighed heavily on our souls we are
> 
> Whole again that you are among us and we celebrate you being here
> again
> 
> As we leave for distant worlds we pledge to respect the lands of
>
> Our neighbours and to act with integrity as ambassadors in peace time
> 
> Of our people travellers with open hearts will always be welcome
> refugees
> 
> From tyranny may seek shelter under our roof and our people will lay
> 
> Down their lives to protect the weak and the just let this be our
> pledge to those
> 
> Inhabitants of this world and all we may ever know we will always
> strive to
>
> Come in peace as we go in peace and you will be welcome on our shores
> forevermore

#Puddle Jumper Console#

From an answer I gave to another question on [why they don't cloak the jumpers before entering the stargate][4] we have more of the ancients leaving messages in english with ancient letters.

Two images are here, taken from the Season 1 episode, *The Defiant One* *, show the left and center of the console, respectively,

[![console right][5]][5]

[![console center][6]][6]

We get the following translation

> Gate protocols must be set before launch sequence. <br>
**Never attempt gate reentry when in cloak m???** [mode?]

#Zero Point Module Interface#

We also have the following image from the Season 1 episode, *Before I sleep*.  The writing on the zero point module station (at the bottom of the picture) translates.

[![Before I sleep][7]][7]

>STAY CLEAR

#Stargate SG-1: Avalon Puzzles#

From the Stargate SG-1 Episode *Avalon, Part 1* the team encounters two puzzles with ancient writing (which Daniel Jackson gives us the translations for during the episode):

[![enter image description here][8]][8]

[![enter image description here][9]][9]

The first (the Vala, Daniel Jackson puzzle in the episode) says

> THE TREASURE IS NOT IN THIS POT
>
> THE UNIVERSE IS INFINITE

The second puzzle (the Cam / Teal'c puzzle) says

> REFLECT ON THE EIGHTFOLD PATH


  [1]: http://stargate.wikia.com/wiki/Ancient_language
  [2]: https://i.sstatic.net/NoDCw.png
  [3]: https://i.sstatic.net/kUE82.jpg
  [4]: http://scifi.stackexchange.com/questions/52854/why-dont-they-cloak-the-jumpers-before-entering-the-gate/97343#97343
  [5]: https://i.sstatic.net/gFdXf.jpg
  [6]: https://i.sstatic.net/hC5rL.jpg
  [7]: https://i.sstatic.net/GXNzh.jpg
  [8]: https://i.sstatic.net/8dxTf.jpg
  [9]: https://i.sstatic.net/MNctz.jpg