Short answer: a calm room that respects a night-shift animal
Put a Roborovski's tank or barred cage in a quiet study, a spare room or an adult's bedroom where evenings are settled and daytime disturbance is low. This is one of the smallest and fastest hamsters, active in bursts through the night, so the room has to work for a creature who sleeps while you are awake and runs while you sleep. A child's bedroom fails both ways: the child disturbs his day sleep with play, and his wheel returns the favour at three in the morning.
Sound carries further at his scale
A Robo's hearing is tuned for a quiet desert, and ordinary rooms are loud at floor or shelf level: television dialogue, a games console fan, a washing machine on spin in the next room. Site the cage on a solid, vibration-free surface — not on top of a tumble dryer, fridge or speaker cabinet — and away from a door that slams. You will know the spot is too lively if he freezes at every sound during his evening emergence instead of moving straight to sand-bathing and foraging.
Heat, light and the desert inheritance
Roborovski hamsters come from arid country and cope poorly with damp and draughts, but direct sun through the glass or plastic of a tank can overheat one dangerously fast, because he cannot burrow out of a hot spot if the whole enclosure is in the sun. Choose a wall away from windows and radiators, with ordinary room light by day and proper darkness at night, so his activity pattern stays anchored. A hallway under a light left on all night quietly erodes that pattern.
Height, lids and other animals
Keep the enclosure where a cat cannot sit on the lid watching him — constant predator attention is a stress even when the lid holds — and never on a high shelf from which a pushed cage could fall. A low, sturdy table is ideal: high enough to keep a dog's nose at a respectful distance, low enough for you to lift the lid safely for spot-cleaning without the lightning dash Robos are famous for becoming an escape across the room.
Choose the surface height with his eyes in mind as well as yours. Robos startle at movement from above far more than at movement level with the tank, so a table around waist height, approached from the front, suits him better than a floor tank that every passing foot looms over. It also keeps his glass or plastic home out of draught level, away from toddlers' hands at floor height, and in the pool of ordinary room light rather than the gloom under a desk, where telling day from evening gets harder for him.
Settling, watching and sharing his routine
For the first days, just watch at dusk from a distance; a Robo who emerges confidently, uses his sand bath and runs freely has read the room as safe. Scatter-feeding and cleaning run to a short weekly rhythm the whole household should follow, since mixed messages mean missed water checks for an animal too small to make his needs obvious. KinsLe's Family Sharing keeps those feeding, water and cleaning notes on his shared profile, so everyone looking after this tiny hamster works from the same routine.