| Author | Titles | | 1.
| Ölçer, Nazan | 2 | | 2.
| Olcina i Aya, Emili | 10 | | 3.
| The Old Chapel Graphic Design (Firma de Design) | 1 | | 4.
| Old Pinakothek in Munich (Alemanha) | 0 | | 5.
| Author is: Alte Pinakothek (Munique, Alemanha) | 8 | | 6.
| Old Truman Brewery (Londres, Grã-Bretanha) | 1 | | 7.
| Old Yacht Club. Sirius Project (Cobh, Irlanda) | 1 | | 8.
| Oldani, Alessandro | 2 | | 9.
| Olden, Wolfgang Schulze, | 2 | | 10.
| Oldenberg, Hermann | 2 | | 11.
| Oldenburg, Claes, 1929-2022 | 11 |
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