Property, Plant and Equipment

At the end of 2015 and 2014, property, plant and equipment at cost and accumulated depreciation were:



(Dollars in Millions)	2015		2014
Land and land improvements	$	780	833
Buildings and building equipment	9,829		10,046
Machinery and equipment	22,511		22,206
Construction in progress	3,528		3,600
Total property, plant and equipment, gross	$	36,648	36,685
Less accumulated depreciation	20,743		20,559
Total property, plant and equipment, net	$	15,905	16,126

The Company capitalizes interest expense as part of the cost of construction of facilities and equipment. Interest expense capitalized in 2015, 2014 and 2013 was $102 million, $115 million and $105 million, respectively.

Depreciation expense, including the amortization of capitalized interest in 2015, 2014 and 2013, was $2.5 billion, $2.5 billion and $2.7 billion, respectively.

Upon retirement or other disposal of property, plant and equipment, the costs and related amounts of accumulated depreciation or amortization are eliminated from the asset and accumulated depreciation accounts, respectively. The difference, if any, between the net asset value and the proceeds are recorded in earnings.