Daniel Hannan has written a very pensive article on what is currently happening, or feared will happen, in Palmyra, Syria, now that it has fallen into the hands of the latest manifestation of the Khawarij, i.e. the so-called Islamic State.
The author intelligently points out, as evidenced by the fact that this site and so many other historical sites have survived to this day, that the Messenger of Allah, may Allah bless him and grant him peace, and the Muslim rulers and scholars who followed saw no need to destroy such places. Rather, they are a testimony to human history and a sign and a reminder to mankind; nothing lasts forever. Allah has said, "Every nation has an appointed time. When their time comes, they cannot delay it a single hour or bring it forward." [Surat al-A'raaf 7:34] ِAllah has also said, "Have they not travelled in the earth and seen the final outcome of those before them? They were more numerous than them and greater in strength and left more and deeper traces on the earth, but what they earned was of no use to them." [Surat al-Ghaafir 40:82]
They are also a reminder of what happens to nations who reject Allah. In verse 83 of the same chapter above, Allah says, "When their Messengers brought them the clear signs, they exulted in the knowledge they had and were engulfed by the very things they mocked."
As for these sites being maintained and used for tourism, Imam Muhammad Saeed Ramadan al-Bouti, may Allah have mercy on him, gave this fatwa a few years ago when he was asked about visiting historical sites in Indonesia, namely those that include Buddhist statues and drawings. The translation of his response is:
"Looking at historical statues and the like, passing by them and sitting by one of their graves is not unlawful. Have you not seen the Pharaonic relics that have remained [i.e. in Egypt] since the days of the Islamic conquest? The Muslims still visit them, pass by them and look at them, and no one has ever declared it unlawful."
Please click on this link for further details and discussion on this fatwa, especially the comments below.
In conclusion, it should be clearly understood that the Khawarij of the "Islamic State" are not following Allah and His Messenger, may Allah bless him and grant him peace, the Companions, may Allah be pleased with them, or the scholars of Muslim Orthodoxy (Ahl as-Sunnah wa al-Jama'ah). They are following Iblis and their desires, plain and simple.
And with Allah is every success.