Columbia subject headings:
Astronomical observatories--Spain--Madrid--Design and construction.
Observatorio Astronómico de Madrid.
Villanueva, Juan de, 1739-1811.
Harvard subject headings:
Astronomical observatories--Spain--Madrid--Design and construction.
Observatorio Astronómico de Madrid.
Villanueva, Juan de, 1739-1811
Princeton subject headings:
Astronomical observatories--Spain--Madrid--Design and construction.
Observatorio Astronómico de Madrid.
Villanueva, Juan de, 1739-1811.