All of the earth is a mosque (prayer place) except the graveyard and the bathroom
Authentic hadithعن أبي سعيد الخدري رضي الله عنه مرفوعًا: «الأرض كُلُّها مسجد إلا المَقْبَرة والحَمَّام».
Abu Sa‘īd al-Khudri (may Allah be pleased with him) reported that the Prophet (may Allah's peace and blessings be upon him) said: "All of the earth is a mosque (prayer place) except the graveyard and the bathroom."
Explanation
All of the earth is a place (suitable) for prayer, except for the place where the dead are buried, and this includes all the area inside the fence of a cemetery; and the place where one bathes with hot water for treatment. An-Nawawi (may Allah have mercy upon him) said: "Prayer in the dwelling places of the devil is disliked by unanimous agreement, such as bars, nightclubs, places where excise taxes are levied, and similar places where sins are openly committed, as well as churches, synagogues, restrooms, etc."
Source · Narrated by Ibn Majah - Narrated by At-Termedhy - Narrated by Abu Daoud - Narrated by Ahmad - Ad-Daarimi
From the Hadith Encyclopedia (hadeethenc.com).