2. A library where a physical copy can be found:
ETH-Bibliothek Hauptgebäude
Rämistrasse 101
HG H 30.1
8092 Zurich
Remark: It is not the first edition of the book. There are editions from 1682 and 1969 for example.
According to swissbib.ch the book is also available physically in many other libraries such as Bibliothèque de Genève, Bibliothèque d’art et d’archéologie Genève, Uni Zürich Klassische Archäologie, Uni Zürich Kunsthistorisches Institut, BCU Lausanne-Dorigny, Uni Neuchâtel – Lettres et sciences humaines and EPF-BIB Lausanne.
Some stable links where the book is available digitally:
ETH e-rara
https://www.e-rara.ch/zut/content/titleinfo/3925844
archive
https://archive.org/details/lesedificesantiq00desg
google books
https://books.google.ch/books?id=K2neAQAACAAJ&dq=antoine+desgodetz&hl
=de&sa=X&ved=2ahUKEwixoPHjk5vsAhWqmIsKHdYhAygQ6AEwAHoECAQQAg
gallica
https://gallica.bnf.fr/ark:/12148/btv1b9058220m/f12.image.r=antoine%20desgodetz
architectura.cesr
https://bibliotheque-numerique.inha.fr/collection/item/6987-redirection