As someone who lives in a building that is 70 years old, I can tell you pipes (brass?) only last about 70 years.. redoing piping in place is a major pain. If the location wasn't so good I'd be gone long ago..
Pipes can last centuries or only years, depending on the material, the temperature, and the solutes in the water — even without getting into cases where the pipes actually break. Both lead and copper (which is more common than brass!) can last centuries in cold water that isn't chemically aggressive. Heck, in Boston a few years back, they dug up some wood pipes that were installed in the 1700s.
We tore our house apart somewhat about eight years ago and had all the pipe work replaced, amongst other things. We also (I did this bit because builder/plumbers generally take the path of least resistance) removed the last two lots of re-plumbing. The house was built in the '20s which is pretty modern hereabouts.
Brass is unlikely, copper is the material. The oldest pipe work I found was steel in our place - it was hard and weighed a fair bit. Copper is maleable, easy to bend and braze joints on to. It does corrode eventually but I think the thin layer of copper oxide that forms then seals in the pure copper, protecting it. The longevity of copper can be seen in the green roofs of some churches which must have looked absolutely stunning before oxidizing.
