وَإِذْ جَعَلْنَا الْبَيْتَ مَثَابَةً لِلنَّاسِ وَأَمْنًا وَاتَّخِذُوا مِن مَّقَامِ إِبْرَاهِيمَ مُصَلًّى ۖ وَعَهِدْنَا إِلَىٰ إِبْرَاهِيمَ وَإِسْمَاعِيلَ أَن طَهِّرَا بَيْتِيَ لِلطَّائِفِينَ وَالْعَاكِفِينَ وَالرُّكَّعِ السُّجُودِ
(Surah Al-Baqarah, 2:125) "And [mention] when We made the House a place of return for the people and [a place of] security. And take, [O believers], from the standing place of Abraham a place of prayer. And We commanded Abraham and Ishmael, saying, 'Purify My House for those who perform Tawaf and those who are staying [there] for worship and those who bow and prostrate [in prayer].'"
الْمَسْجِدُ الْحَرَامُ
The name of the first and the holiest mosque is Al-Masjid Al-Haram (المسجد الحرام), which is in Makkah, where the Kaaba is located.
وَقَالَ رَسُولُ اللَّهِ ﷺ: "أَوَّلُ مَسْجِدٍ وُضِعَ فِي الْأَرْضِ الْمَسْجِدُ الْحَرَامُ"
The Prophet Muhammad ﷺ said: "The first mosque built on the earth is Al-Masjid Al-Haram." (Sahih al-Bukhari)
This means the very first mosque that Allah created and that people built to worship Him is the sacred mosque in Makkah, around the Kaaba. It is the center of the Muslim world and the place where Muslims face during prayer.
**Takeaway:** The first and most important mosque is Al-Masjid Al-Haram in Makkah, and it is the direction Muslims face when they pray. Visiting or praying in this mosque is very special in Islam. Allah knows best.