Is it permissible to build a hotel and restaurant free of forbidden things and to allocate a room for prayer therein, while disregarding the appearances and intentions of the customers, or is that considered cooperation in sin and aggression due to the sins of vacationers outside the hotel? And if it is not permissible, is it permissible to sell the land to someone who will build on it for profit?

If the hotel is free of illicit activities and corruption, there is no objection to building it anywhere, provided that its management maintains its cleanliness from religious transgressions. You will not be harmed by what holidaymakers do outside it, if you fulfill your duty of advising, enjoining good, and forbidding evil.

However, selling land to someone who will build a hotel on it that does not adhere to Islamic ethics is a mistake. The landowner should build a model hotel that adheres to the Sharia (definition) to close the door to corruption and present a clean example.

If he cannot control the hotel to prevent it from becoming a hotbed of corruption, then it is not permissible to build it.