What is on the top of Wellington Arch?

The Wellington Arch, also known as the Constitution Arch or as the Green Park Arch, is a Grade I-listed triumphal arch by Decimus Burton that forms a centrepiece of Hyde Park Corner in central London, between the corner where Hyde Park meets Green Park.

Was Wellington Arch ever the entrance to Buckingham Palace?

Set in the heart of royal London, Wellington Arch was built as an original entrance to Buckingham Palace, later becoming a victory arch proclaiming Wellington's defeat of Napoleon.