First, elect to save your tax return as a PDF to your computer. Elect to save *EVERYTHING* and not just the forms required for filing or for your records.
Then open the PDF and look for the IRS Form 4562. There are two of them and they both print in landscape format. One of them is titled "Amortization and Depreciation Report". The cost basis is on there. Add together the amounts in the "Cost (Net of Land)" column and the "Land" column for the total cost basis. The amount in the "Cost (Net of Land)" column is the value of the structure and is the amount being depreciated.