There was no more sacred space, according to Hebrew Scripture, than a certain place that appeared to be empty. It was the small area atop the Ark of the Covenant. There within the Holy of Holies was the most significant space in all Israel. What appeared empty was in reality meaning-filled, for all other space was determined by that place.
Sacred space can be that specific, that exact, that small and sheltered.
Or sacred space may extend outward as far as the cosmic totality does. That space is sacred where heaven and earth meet, and where God and humanity commune. Somewhere between the heavens and the Holy of Holies we all live. Sacred space, once set apart, habitually moves outward into all areas of life. A lectionary text, for example, sees all the spaces occupied by a marriage as also being filled by the Creator.