difficult clues !

[Kirkpatrick]

Pottery & porcelain factory founded in Naples c1760
g*u*t*n*a*i (11 letters)
Porcelain factory founded near Weimar c1777
i*m*n*u (7 letters)
Orthodox Jewish college or seminary
y*s*i*s (7 letters)

[Kirkpatrick]

discovered "yeshiva" -sorry but I have shown "s" as last letter - but it should been an "a" - factories still bother me though !

[FoxLee2]

ilmenau

[Kirkpatrick]

thanks FoxLee - just minutes before your answer was posted I found the answer on a remote site- nevertheless you're a good'un for taking the trouble. After much trawling I now think the Naples factory is a secret underground bunker - unmapped !