A 250 nm Pentium III processor may not be the most interesting piece of hardware anymore, at least if you depend on running such an antique in your computer.
However, if you have access to an electron microscope, even this old CPU can provide stunning imagery.
A science teacher examined the core of a Pentium III CPU. He removed the package via a power saw and used a scalpel to open the actual CPU cover. The interesting part begins with images that were taken using an optical microscope, enabling him to peek through the holes of the cover to see the connecting points between the CPU and the circuit board. The optical microscope took him close enough to see the different layers of the chip.
He transitioned to an electron microscope and drilled down to a level that we typically only get to see in pictures that are provided by the manufacturer itself. The examination ended at a resolution that allowed him to spot structures as small as 2000 nm, which is not close enough to actually see the transistors, but provides stunning detail of the CPU, even at a 10,000 nm level. Head over to SciencyStuff to see more pictures.
Even if we deal with CPUs on a daily basis (and the Pentium III is more than 11 years old), this is something we don't see too often.