Nouns ending in -ade are usually feminine.
The suffix often marks an action, group, or product.
Is ambassade masculine or feminine?
l'ambassade
The rule behind it
92.3% of -ade nouns are feminine
In context
Longue ambassade et long voyage aboutissent à cocuage.
Long embassy and long travel lead to unfaithfulness.
L'ambassade refuse l'asile aux réfugiés politiques.
The embassy denies asylum to political refugees.
Il a accès à l'ambassade américaine.
He has access to the American Embassy.