The Hindu temple architecture is an open, symmetry driven structure, with many variations, on a square grid of padas, deploying perfect geometric shapes such as circles and squares. A Hindu temple consists of an inner sanctum, the garbha griha or womb-chamber, where the primary idol or deity is housed along with Purusa. The garbhagriha is crowned by a tower-like Shikhara, also called the Vimana. The architecture includes an ambulatory for parikrama (circumambulation), a congregation hall, and sometimes an antechamber and porch.