House of Lords - Palace of Westminster
This side is the House of Commons. The Victoria Tower is on the right. The Sovereign's Entrance below that.
The Palace of Westminster is a Grade I listed building and a World Heritage Site.
The entrance for the general public / tourists is in the middle (possibly that new bit where the Police officers are)
The public entrance is called the St Stephen's Entrance. To enter you have to either, book well in advance from your MP (say 7 to 8 weeks) or queue up at the St Stephen's entrance.