What is "grilles"

Usage examples of "grilles".

It was a gutter, originally for shit and now for rainwater, a six-inch channel between the paving slabs that sluiced through grilles into the undercity at the furthest end.

When we have to secure the fortress, we just lift these grilles and give the beasts access to the whole outer ward.

It was a complex procedure, involving an alarm system and an arrangement of steel grilles, and she performed it with painstaking concentration.