Yes, you can check into a hotel at 3:00 AM, but it requires careful coordination and is almost never a "free" early check-in. Most hotels that operate with a 24-hour front desk can accommodate a 3:00 AM arrival, but you must have a reservation for the night before. For example, if you arrive at 3:00 AM on a Tuesday, you must have booked a room starting on Monday afternoon. If you only have a reservation starting Tuesday (with a standard 3:00 PM check-in), the hotel will likely not have a room ready for you, or they will charge you for an extra night. It is absolutely essential to notify the hotel in advance if you plan to arrive after midnight; many hotels will mark you as a "no-show" and cancel your reservation if you haven't checked in by 10:00 PM or 2:00 AM. By informing them, they will place a note on your file and ensure your room is held. Additionally, while the main doors of some hotels may be locked for security at that hour, there is usually an intercom or a security guard to let you in. Checking in at 3:00 AM is common for late-night flight arrivals, but it is always a "full night" charge rather than a half-day or hourly rate.