Mishneh Torah, The Chosen Temple 6:14משנה תורה, הלכות בית הבחירה ו׳:י״ד
Any place which was not [consecrated] with all the above [elements] and according to the above procedure is not thoroughly consecrated. Though Ezra offered two thanksgiving offerings [to dedicate the city,] he merely carried out a testimonial act. The Sanctuary was not consecrated through his deeds, for neither a King nor the Urim V'Tumim were present there.[If so,] how was [the Second Temple] consecrated? With the first consecration performed by Solomon, for he consecrated the Temple Courtyard and Jerusalem, for that time and for eternity.
Hasagot HaRa'avad on Mishneh Torah, The Chosen Temple 6:14:1השגות הראב"ד על משנה תורה, הלכות בית הבחירה ו׳:י״ד:א׳
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Mishneh Torah, The Chosen Temple 7:7משנה תורה, הלכות בית הבחירה ז׳:ז׳
Even though, the Temple is now in ruin because of our sins, a person must hold its [site] in awe, as one would regard it when it was standing.[Therefore,] one should only enter a region which he is permitted to enter. He should not sit in [the area of] the Temple Courtyard, nor should he act frivolously when standing before [the place of] the eastern gate, as [implied by Leviticus 19:30]: "You shall observe My Sabbaths and you shall revere My Sanctuary." [Explaining the analogy between the two commands, the Sages comment:] "Just as the observance of the Sabbath [applies] for eternity, so too, the reverence for the Temple must be eternal. Even though it is in ruin, it remains holy."