During a papal conclave, the cardinals stay at the Domus Sanctae Marthae, a guesthouse within Vatican City near St. Peter's Basilica. This modern residence was specifically built to house cardinals comfortably during conclaves, replacing the previous practice of lodging them in small, uncomfortable rooms in the Apostolic Palace

. The building has about 131 rooms, including suites and single rooms, each with private bathrooms and basic furnishings

. Because the number of cardinal electors can exceed the number of rooms, additional accommodations are arranged in nearby Vatican facilities such as the old Santa Marta building and other Vatican-owned apartments

. Cardinals are assigned rooms by lot, and strict rules are enforced to keep them secluded from the outside world, including disconnection of phones, internet, and television

. The cardinals travel by bus from Domus Sanctae Marthae to the Sistine Chapel, where the voting takes place

. The residence also houses support staff for the conclave, including cooks, doctors, and confessors, who serve the cardinals during their stay

. In summary, cardinals stay at the Domus Sanctae Marthae during conclaves, a Vatican guesthouse designed to provide simple but comfortable lodging and seclusion throughout the election process