Yes, they exist, but they are not yet common. A few cities and private developments have tested benches that can be lowered into the pavement or folded away after hours, usually to open up pedestrian space, make street cleaning easier, or allow delivery vehicles to pass. You are more likely to see retractable or fold-away benches in plazas, transit stations, and shopping districts than on an ordinary residential street.
The most practical designs use a shallow metal trough or casing set into the ground. The bench seat sits on a scissor lift, a hydraulic piston, or a gas-spring mechanism. When staff press a control or a timer activates, the bench sinks down until the top is flush with the pavement. The surface is then safe to walk over and easy to clean. Some systems are fully automatic, while others are operated by maintenance crews with a key or remote.
Other disappearing benches are less dramatic. Many fold flat against a wall, flip up like a jump seat, or slide under a planter. These are cheaper and more common because they do not require cutting a deep pit, installing drainage, or protecting mechanical parts from rainwater and debris. True below-ground benches are more expensive and need regular maintenance, which is why they are still rare.
A few public-space projects use these benches to discourage sleeping or loitering at night, but that is only part of the story. Many designers use them simply because a plaza needs seating during lunchtime but clear space for events, markets, or cleaning at night. The same logic applies to narrow sidewalks where a permanent bench would block a fire exit or a delivery route.
The main drawbacks are cost, drainage, and long-term reliability. If dirt, leaves, or ice get into the mechanism, the bench can jam halfway. That is why successful installations use sealed housings, heating in cold climates, and scheduled inspections. For this reason, you should expect underground or fold-away benches to appear in signature urban projects rather than every street corner.
So if you are asking whether street benches can fold into the ground to clear space at night, the answer is yes. They are real, they work, and they are slowly becoming more popular, but they remain a premium space-saving solution rather than a standard piece of street furniture.