QuickLinks -- Click here to rapidly navigate through this document

Exhibit 12

Statement re: Calculation of Ratios of Earnings to
Combined Fixed Charges and Preferred Stock Dividends
(Dollars in thousands)

		Six Months Ended June 30, 2003			Year Ended December 31, 2002			Year Ended December 31, 2001			Year Ended December 31, 2000			Year Ended December 31, 1999			Year Ended December 31, 1998
Net income from continuing operations less preferred dividends		$	69,264		$	158,028		$	226,010		$	211,925		$	139,636		$	90,871
Preferred dividends			17,504			45,053			52,442			48,981			42,604			19,833
Earnings from land and depreciated property dispositions			(11,146	)		(2,340	)		(45,708	)		(60,692	)		(10,012	)		(1,351	)
Operating Partnership minority interest			7,587			18,196			31,904			31,916			19,811			12,241
Interest expense			67,377			116,570			111,419			131,048			86,757			60,217
	Earnings before fixed charges		150,586			335,507			376,067			363,178			278,796			181,811
Interest expense			67,377			116,570			111,419			131,048			86,757			60,217
Preferred dividends			17,504			45,053			52,442			48,981			42,604			19,833
Interest costs capitalized			3,306			13,529			25,859			32,980			26,017			8,546
	Total fixed charges		88,187			175,152			189,720			213,009			155,378			88,596
Ratio of Earnings to Fixed Charges			2.13			2.58			2.74			2.21			2.47			2.64
Ratio of Earnings to Combined Fixed Charges and Preferred Dividends			1.71			1.92			1.98			1.70			1.79			2.05

QuickLinks

Statement re: Calculation of Ratios of Earnings to Combined Fixed Charges and Preferred Stock Dividends (Dollars in thousands)