For example:
A Centurion outfit, like this one:
http://www.renderosity.com/mod/gallery/index.php?image_id=1661674

Buildings like these ones (found on another website for 3ds max).

Cheers
Mike aka rofocale

Have a look to RDNA in the Zero Price section.
There is a complete roman female outfit for V2 and also a harem outfit which could fit also to that time. And a male temple slave costume for M2, not directly roman but versatile.

For the female roman outfit a additional texture set is found here in the freestuff section a week back.

Continuing on what JoEtzold said about the V2 Roma outfit, if you have CrossDresser from Evilennocence it converts wonderfully to V3 and TY2. Can't vouch for others since I haven't done them.

Mike, there's the wonderful Julius Caesar at Content Paradise. It's an outfit for the G2 males, but it can be easily converted with something like Wardrobe Wizard from PhilC or Clothes Convertor at Daz.
I own the Caesar too and converted the outfit for David - perfect!
Here's the link to the Caesar:
http://www.contentparadise.com/productDetails.aspx?id=274
Hope this helps!
~Sassy~

Go to 3dwarehouse.com and type in Roman..And stand back...

3dwarehouse seems to be under construction.......and for sale.....

http://sketchup.google.com/3dwarehouse/

Was just there  try this one..Sorry..

Xurge 3D also has a good Roman soldier outfit!

Thank´s for all the suggestions!

JoEtzold and nickedshield: Thank you, I had forgotten about that section at RDNA!
I also remember that I can use the Empire era dress for V3, (RDNA).

Jedi_Padawan: I have that excellent product already and I also have the Roman senator outfit!
I also have the WW by Phil and it is a fantastic tool :)

3eighty: Fine suggestion with the "sketchup" site, will be great for inspiration but I don´t think I can use those files in Poser :(

thefixer: Oh yeh, I have that Caesar outfit by Sergio (xurge). In fact the link I provided leeds
to a render made by xurge. But that Centurion outfit is not for sale...

I already have the Roman Legionary by adh3d and is planning to buy the Roman Officer.

I have also found some stuff at the free stuff section.
...and I am also aware of the other great Roman themed items here at the marketplace.

Thank you guys for the suggestions :)
Please keep on with it!

Mike

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Poserworld has some Roman stuff for Dork and Posette too.

I've been asking for Roman clothing from like the movie Gladiator for a while now. (The senator's robes would be really nice) Plus we need to have some buildings to go along with it.

But in the meantime:

Here is a Roman Officer:
http://www.renderosity.com/mod/bcs/index.php?ViewProduct=67168&keyword=roman

Legionary:
http://www.renderosity.com/mod/bcs/index.php?ViewProduct=61828&keyword=roman

Gladiator:
http://www.renderosity.com/mod/bcs/index.php?ViewProduct=62300&keyword=roman

Now they're all for Apollo (which is free though) ... but I guess they could be converted to whatever figure you're using.

Oh, there is a coliseum interior:
http://www.renderosity.com/mod/bcs/index.php?ViewProduct=59215&keyword=roman

And DAZ has a spartan soldier (m4 & V4) ..