Torre Jaume I on the Barcelona Cableway. The cableway was built in 1929 and I am concinved that all the original parts are still being used. It is old, rickety and a little scary, but hugely fun in a retro kind of way.
This tower is 107 metre high, and is the midpoint of the cable car. In theory, you can climb out and stand on the observation platform, but our car went straight past. It still gives you a great view of Barcelona and the harbour area, but a one-way trip is probably sufficient.