What happened to the Mishkan?

Question

Where is the Mishkan today (i.e. where are its components)? What happened to the set of tablets that were housed inside?

This post suggests that the Mishkan was destroyed in Shiloh, but does not give any definitive answer.

Answer 1

Q1

Where is the Mishkan today?

The Mishkan went from Shiloh to Nobh, then to Gibh'on and then was replaced by the Miqdash in Yerushalayim. H. Beth ha-Behirah 1:2-3:

כיון שנכנסו לארץ, העמידו המשכן בגלגל ארבע עשרה שנה שכבשו ושחלקו. ומשם באו לשילה, ובנו שם בית של אבנים; ופרסו יריעות המשכן עליו, ולא הייתה שם תקרה. ושלוש מאות ותשע ושישים שנה, עמד מקדש שילה. וכשמת עלי, חרב ובאו לנוב ובנו שם מקדש; וכשמת שמואל, חרב ובאו לגבעון ובנו שם מקדש. ומגבעון באו לבית העולמים. וימי נוב וגבעון, שבע וחמישים שנה. כיון שנבנה המקדש בירושלים--נאסרו כל המקומות כולן לבנות בהן בית לה', ולהקריב בהן קרבן; ואין שם בית לדורי הדורות אלא בירושלים בלבד, ובהר המורייה שבה--שנאמר "ויאמר דויד--זה הוא, בית ה' האלוהים; וזה מזבח לעולה, לישראל" (דברי הימים א כב,א), ואומר "זאת מנוחתי, עדי עד" (תהילים קלב,יד).

After [the Jews] entered The Land [of Israel], they erected the Sanctuary in Gilgal during the fourteen years in which they conquered and divided [the land]. From there, they came to Shiloh, built a house of stone, and spread the curtains of the Sanctuary over it. It did not have a roof. The sanctuary of Shiloh stood for 369 years. When Eli died, it was destroyed.[Afterwards,] they came to Nobh and built a sanctuary. When Samuel died, it was destroyed. And they came to Gibh'on and built a sanctuary. From Gibh'on, they came to the eternal structure [in Jerusalem]. The days [the sanctuary stood] in Nov and Givon were 57 years.

According to this it would seem that the Mishkan at Shiloh and Nobh were destroyed. It was then rebuilt in Gibh'on. From Gibh'on we transitioned to the Miqdash in Yerushalayim. The components of the Mishkan which would not naturally be incorporated into a permanent structure were sequestered away, as it states in Sotah 9a:

דאמר מר: משנבנה מקדש ראשון, נגנז אהל מועד, קרשיו, קרסיו ובריחיו ועמודיו ואדניו. היכא? אמר רב חסדא אמר אבימי: תחת מחילות של היכל

After the first Temple was erected, the Tent of Meeting was stored away, its boards, hooks, bars, pillars and sockets. Where [were they stored]? — R. Hisda said in the name of Abimi: Beneath the crypts of the Heikhal.

According to this tradition, those components which were not incorporated into the Miqdash were sequestered away beneath the outer sanctum (Heikhal). I do not believe we have information on what happened to those components after the destruction of the first Miqdash.

Q2

What happened to the set of tablets that were housed inside?

The luhoth (tablets) were within the Aron (Ark), what happened to the Aron after the destruction of the first Miqdash is a bit of a mystery. The Rambam states (H. Beth ha-Behirah 4:1):

אבן הייתה בקודש הקודשים במערבו, ועליה היה הארון מונח, ולפניו צנצנת המן ומטה אהרון. ובעת שבנה שלמה את הבית, וידע שסופו ליחרב, בנה מקום לגנוז בו הארון למטה, במטמונייות עמוקות ועקלקלות; ויאשייהו המלך ציווה וגנזו במקום שבנה שלמה, שנאמר "ויאמר ללויים המבינים לכל ישראל הקדושים לה', תנו את ארון הקודש בבית אשר בנה שלמה בן דויד מלך ישראל--אין לכם משא, בכתף; עתה, עבדו את ה' אלוהיכם . . ." (דברי הימים ב לה,ג). ונגנז עימו מטה אהרון והצנצנת, ושמן המשחה; וכל אלו לא חזרו בבית שני. ואף אורים ותומים שהיו בבית שני--לא היו משיבין ברוח הקודש ולא היו נשאלין בהן, שנאמר "עד עמוד כוהן, לאורים ותומים" (ראה עזרא ב,סג; נחמיה ז,סה); ולא היו עושין אותן אלא כדי להשלים שמונה בגדים לכוהן גדול, כדי שלא יהא מחוסר בגדים.

The Ark was placed on a stone in the western portion of the Holy of Holies. The vial of manna and Aharon's staff were placed before it. When Solomon built the Temple, he was aware that it would ultimately be destroyed. [Therefore,] he constructed a chamber, in which the ark could be entombed below [the Temple building] in deep, maze-like vaults. King Josiah commanded that [the Ark] be entombed in the chamber built by Solomon, as it is said (II Chronicles 35:3): "And he said to the Levites who would teach wisdom to all of Israel: 'Place the Holy Ark in the chamber built by Solomon, the son of David, King of Israel. You will no [longer] carry it on your shoulders. Now, serve the Lord, your God.'When it was entombed, Aharon's staff, the vial of manna, and the oil used for anointing were entombed with it. All these [sacred articles] did not return in the Second Temple. Similarly, the Urim V'Tumim that existed in the Second Temple did not answer with Ruach HaKodesh (Divine inspiration) and questions were not asked of them, as stated [in Ezra 2:63]: "until a priest will arise with the Urim V'Tumim." [In the Second Temple,] they only made them to fulfill the requirement of eight garments for the High Priest. Thus, the High Priest would not lack one of the required garments.

According to this view, the Aron is still somewhere deep beneath the earth on Har ha-Bayith (the Temple Mount) in Yerushalayim.

Answer 2

Where are its components?

The Rambam writes (Hilchos Beis HaBechirah, Halacha 1:2):

From Givon, they came to the eternal structure [in Jerusalem].

The HarHamoriyah, a commentary written by Rabbi Meir Yonah Brancki (1817 - 1891 CE) writes on halacha 2 from Mishneh Torah; Hilchos Beis HaBechirah, chapter 1 that the parts of the Mishkan were disassembled and put away, e.g. stored away (my own, loose translation of this piece). Where they are now, is bit of a mystery. If they still exist. Maybe (my own idea) the materials were used in building the Holy Temple.