Columbia subject headings:
Harvard subject headings:
Architecture, Domestic--Greece--Peloponnesus (Peninsula)
Fortification--Greece--Peloponnesus (Peninsula)--Pictorial works.
Peloponnesus (Greece : Peninsula)--Buildings, structures, etc.
Towers--Greece--Peloponnesus (Peninsula)--Pictorial works.
Princeton subject headings:
Architecture, Domestic--Greece--Peloponnesus.
Fortification--Greece--Peloponnesus.
Tower houses--Greece--Peloponnesus.
Towers--Greece--Peloponnesus.