Why is it der Wedding?

Wedding ends in -ing. Most nouns with this ending are neuter (84% take das), but Wedding is an exception: der Wedding.

The other -ing exceptions
Sense 1
der

Meaning

[1] A Berlin district

[1] ein Berliner Stadtteil

Examples

[1] "A seriously injured man have discovered police officers in Wedding"

[1] „Einen schwer verletzten Mann haben Polizisten im Wedding entdeckt.“
Grammar note

The Wedding is one of the few place names that are used in German with article

Declension

1 Singular Plural
Nominativ der Wedding —
Genitiv des Weddings —
Dativ dem Wedding —
Akkusativ den Wedding —

Dictionary entries include material from Wiktionary. Wiktionary