8-K

                                  UNITED STATES
                       SECURITIES AND EXCHANGE COMMISSION
                             WASHINGTON, D.C. 20549

                                    FORM 8-K

                                 CURRENT REPORT
                       Pursuant to Section 13 or 15(d) of
                       The Securities Exchange Act of 1934

       Date of Report (Date of earliest event reported): December 10, 2003

                           IRON MOUNTAIN INCORPORATED
             (Exact name of registrant as specified in its charter)

                                  PENNSYLVANIA
                 (State or other jurisdiction of incorporation)

         1-13045                                          23-2588479
(Commission File Number)                       (IRS Employer Identification No.)

                               745 Atlantic Avenue
                           Boston, Massachusetts 02111
          (Address of principal executive offices, including zip code)

                                 (617) 535-4766
              (Registrant's telephone number, including area code)

Item 5. Other Events and Regulation FD Disclosure

On December 10, 2003, the Company issued a press release announcing that it
signed an agreement with Mentmore plc to acquire Mentmore's 49.9% equity
interest in Iron Mountain Europe Limited. Completion of this transaction will
give Iron Mountain 100% ownership of Iron Mountain Europe Limited. A copy of the
Company's press release is attached hereto as Exhibit 99.1 and is incorporated
herein by reference.

Item 7. Financial Statements and Exhibits

(c) Exhibits.

Exhibit No.       Item
- -----------       ----
99.1              Press release dated December 10, 2003.

SIGNATURES

Pursuant to the requirements of the Securities Exchange Act of 1934, the
Registrant has duly caused this report to be signed on its behalf by the
undersigned thereunto duly authorized.

                               IRON MOUNTAIN INCORPORATED
                               (Registrant)

                               By: /s/ Jean A. Bua
                                   -------------------------------------------
                               Name:  Jean A. Bua
                               Title: Vice President and Corporate Controller

      Date: December 10, 2003

EX-99.1

                                                                    Exhibit 99.1

       Iron Mountain Incorporated Announces Agreement to Acquire Remaining
                    Interest in Iron Mountain Europe Limited

         Mentmore plc Agrees to Sell 49.9% Stake for BPS 82.5 Million

    BOSTON and LONDON, Dec. 10 /PRNewswire-FirstCall/ -- Iron Mountain
Incorporated (NYSE: IRM), the leader in records and information management
services, announced today that it has signed an agreement with Mentmore plc to
acquire Mentmore's 49.9% equity interest in Iron Mountain Europe Limited
("IME") for total consideration of BPS 82.5 million in cash.  IME is the
European joint venture established in 1999 by Iron Mountain and Mentmore to
pursue records management opportunities in Europe and is now believed by the
partners to be the largest pan-European records management company with more
than 15,000 customer accounts in 38 markets in the U.K. and on the European
continent.  The transaction is expected to close in February 2004 and is
subject to the approval of the Mentmore shareholders and other customary
conditions.

    Included in the BPS 82.5 million purchase price is the repayment of all
trade and working capital funding owed to Mentmore by IME.  This transaction
also releases Mentmore from any future funding obligations related to IME.
Completion of this transaction will give Iron Mountain 100% ownership of IME,
affording it full access to all future cash flows and greater strategic and
financial flexibility.  Iron Mountain expects to fund the acquisition
consideration with existing cash on hand and borrowings under its revolving
credit facility.

    Nicholas P. Smith, Chairman of Mentmore, commented, "We have had a very
productive partnership with Iron Mountain and believe the prospects for IME to
be sound. However, given our recent strategic review of Mentmore's current
circumstances and the availability of robust investment opportunities for us
in the public personal storage industry, we felt it best for Mentmore's
shareholders to realize the value from our investment in IME at this time."

    Richard Reese, Chairman and CEO of Iron Mountain, stated, "Iron Mountain
is fortunate to have entered the European records management market with
Mentmore as our partner.  They have been great partners over the past five
years and together we have built a tremendous business.  We wish everyone at
Mentmore well in their new strategic endeavors and thank them for their
contribution to the success of IME."  Mr. Reese continued, "This deal comes at
a time when the future is very bright for IME.  We look forward to taking full
advantage of the attractive growth opportunities before us in the European
market."

    The transaction is not expected to close until early 2004, and therefore
will not have any impact on the 2003 consolidated financial statements of Iron
Mountain Incorporated.  Additionally, there should be no impact on Iron
Mountain's revenue or operating income before depreciation and amortization
(OIBDA) post-closing since IME's financial results are already fully
consolidated into Iron Mountain's results.  Since the acquisition of the
minority stake in IME will be accounted for using the purchase method of
accounting, 49.9% of the net assets of IME will be adjusted to reflect their
fair market value if different from their current carrying value.  As a
result, this transaction will increase depreciation and amortization expenses
beginning in 2004.  Once the transaction has been completed and the related
trade and working capital funding has been paid off, the only impact on Iron
Mountain's consolidated financial statements will be the increased
depreciation and amortization expense just described, the increased debt used
to fund the acquisition and related interest expense and the elimination of
the minority interest in earnings of subsidiaries, net and the minority
interest liability related to Mentmore's ownership of IME.  The net effect of
these changes is not expected to be material to the Iron Mountain consolidated
financial statements.  Iron Mountain will provide additional information
during its fourth quarter earnings conference call in February 2004.

    About Iron Mountain

    Iron Mountain Incorporated is the world's trusted partner for outsourced
records and information management services.  Founded in 1951, Iron Mountain
has grown to service more than 150,000 customer accounts throughout the United
States, Canada, Europe and Latin America. Iron Mountain offers records
management services for both physical and digital media, disaster recovery
support services and consulting services -- services that help businesses save
money and manage risks associated with legal and regulatory compliance,
protection of vital information, and business continuity challenges. For more
information, visit www.ironmountain.com.

SOURCE  Iron Mountain Incorporated
    -0-                             12/10/2003
    /CONTACT:  Stephen P. Golden, Director of Investor Relations of Iron
Mountain Incorporated, +1-617-535-4799/
    /Photo: http://www.newscom.com/cgi-bin/prnh/20030505/IRMLOGO
            AP Archive:  http://photoarchive.ap.org
            PRN Photo Desk, 888-776-6555 or 212-782-2840/
    /Web site:  http://www.ironmountain.com /
    (IRM)

CO:  Iron Mountain Incorporated; Mentmore plc; Iron Mountain Europe Limited;
     IME
ST:  Massachusetts, England
IN:  PUB FIN
SU:  TNM