I am having trouble doing a Classified Balance Sheet. Is Accumulated Depreciation liability or assets?

Accumulated Depreciation is an asset.

More specifically, it is a contra-asset. It is an asset, but if behaved contrary to a normal asset.

So on the Balance Sheet, it can look like this:

Cash 1,000
AR 1,500
Supplies 500
Building 80,000
Less Accumulated Depreciation 20,000

Total Assets 63,000 (which is 1,000 + 1,500 + 500 + 80,000 – 20,000)