Exhibit 23.1 [LETTERHEAD OF ARTHUR ANDERSEN LLP] Consent of Independent Public Accountants As independent public accountants, we hereby consent to incorporation by reference in this Registration Statement on Form S-8 of our report, dated January 27, 2000, included in Port Financial Corp.'s (formerly Cambridgeport Mutual Holding Company and subsidiaries) Form 10-K for the year ended December 31, 1999 and to all references to our Firm included in this Registration Statement. /s/ ARTHUR ANDERSEN LLP Boston, Massachusetts October 23, 2000