Columbia subject headings:
Cave architecture--Conservation and restoration--Europe--Congresses.
Cave architecture--Conservation and restoration--Italy--Congresses.
Cave architecture--Europe--Congresses.
Cave architecture--Italy--Congresses.
Fountains--Europe--Congresses.
Fountains--Italy--Congresses.
Garden structures--Europe--Congresses.
Garden structures--Italy--Congresses.
Nymphaea (Architecture)--Europe--Congresses.
Nymphaea (Architecture)--Italy--Congresses.
Harvard subject headings:
Cave architecture--Europe.
Cave architecture--Italy.
Garden structures--Europe.
Garden structures--Italy.
Princeton subject headings:
Cave architecture--Europe.
Cave architecture--Italy.
Garden structures--Europe.
Garden structures--Italy.