The base font is could be any of many Gothic sans serif designs. Here is one by Filmotype that was used in movies: Glenlake as digitized by Mark Simonson.
Life of Brian was made in 1979. IIRC the cracked monumental lettering dates from then. If so, almost certainly made by a graphic artist working without computer programs. As for the 3d effect this can be done direct on a font using a program such as Fontlab. To find out how to get the desired cracking effect using a computer, I suggest you consult any good book on Photoshop techniques or a few web searches for tutorials on textures etc.
Good luck.
Don