[{"_id":1,"name":"city1","districts":[{"id":5,"name":"district 1","neighborhoods":[{"id":309,"name":"neighborhood 1"}]},{"id":6,"name":"district 2","neighborhoods":[{"id":52280,"name":"neighborhood 2"}]}]},{"_id":2,"name":"city2","districts":[{"id":5,"name":"district 3","neighborhoods":[{"id":309,"name":"neighborhood 3"}]},{"id":6,"name":"district 4","neighborhoods":[{"id":52280,"name":"neighborhood 4"},{"id":52287,"name":"neighborhood 5"}]}]}]

db.collection.aggregate([{$match:{name:"city1"}},{$unwind:"$districts"},{$match:{"districts.name":"district 1"}},{$unwind:"$districts.neighborhoods"},{$match:{"districts.neighborhoods.name":"neighborhood 1"}}])