About the letters :
two ways to do it .. if you are going to get really close to the letters, then model them.
if your gonna watch the gate from distance then you can use bumpmaps or displacement maps..
but it all depends on the scenery..
about the gate itself:
I would draw a crosssection of the gate and use revolve.
Carsten Lind
Senior 3D Artist,
Maya Software Manager & Maya Instructor
LEGO Systems A/S