I was lucky enough to be able to book a table at the 40|30 Restaurant in the Gherkin, Norman Fosters landmark building.
This is normally for private dining only, so not easy to get in, but if you ever get the chance, go for it. The views and the architecture are breathtaking, the photographs do not do it justice. However what really surprised me was the food, it actually managed to compete, we went for the tasting menu with matching wines, so not a cheap night out by any means.