ArchitectureCraft provides a wide variety of good-looking architectural features including sloped roofs, glazable window frames, arches and other rounded blocks, classical pillars and entablatures, and railings for balconies and stairways. ArchitectureCraft blocks may be made from almost any vanilla material and many materials added by mods as well.
Home page: http://www.cosc.canterbury.ac.nz/greg.ewing/minecraft/mods/ArchitectureCraft/
Minecraft Forum thread: http://www.minecraftforum.net/forums/mapping-and-modding/minecraft-mods/2489461-architecturecraft-1-3-1-for-minecraft-1-8-8-1-8-9
Forge Forums thread: http://www.minecraftforge.net/forum/index.php?topic=32607.0