This modest museum remembers Alexander Popov, the Russian physicist often credited in Russia as one of the pioneers of radio communication. Kronstadt's naval setting makes the subject feel less abstract, since wireless signalling was quickly bound up with ships, storms, and military communications.
It is a specialist stop rather than a universal must-see. Come if you are interested in science history, radio, or the technical side of the Baltic naval base; otherwise fold it into a broader Kronstadt walk rather than crossing town for it alone.