In which location is the UK parliament based?

Westminster is the heart of the UK's political power. Think of it as the British equivalent of Washington D.C. in the United States. The UK Parliament, which is responsible for making laws for the whole of the United Kingdom, is based in the Palace of Westminster. This iconic building, with its famous clock tower housing Big Ben, sits on the bank of the River Thames in London. It's been the seat of English, and later British, government for almost a thousand years. Now, Holyrood is where the Scottish Parliament meets in Edinburgh, Senedd is the Welsh Parliament in Cardiff, and Stormont is the Northern Ireland Assembly in Belfast. These are all important devolved bodies, but they only make laws for their specific regions. So, when we're talking about the UK Parliament as a whole, it's definitely Westminster.
Think of the famous Abbey or the Big Ben, both are in this location.