Rashi on Genesis 35:27/רש"י על בראשית ל״ה:כ״ז

1ממרא MAMRE — the name of the plain.

2קרית הארבע KIRIATH-ARBA— the name of the city.

3ממרא קרית הארבע therefore means “to the plain of Kiriath-arba”. If you say that it should have written ממרא הקרית ארבע (that Kirjath-arba being one name the definite article should be placed in front of it) then I reply that this is the rule in Biblical Hebrew: in every case of a name compounded of two words, such as this, and such as בית לחם and אבי עזר and בית אל, when it is necessary to prefix the definite article (in order to determine the name) it is prefixed to the second element of the name — thus (1 Samuel 16:1)בית הלחמי the Bethlehemite; (Judges 6:24) “in Ophrah (אבי העזרי) of the Abiezrites”; (1 Kings 16:34) “did Hiel the Bethelite (בית האלי) build”.