Another great free thing to do, although you do have to register before hand. Through airport style security then up in a lift to the roof and dome. Grab a leaflet showing the skyline and notable buildings and enjoy the views. Walk up the spiral walkway up to the top of the dome , there's and up walkway and a down walkway by the way. Nice restaurant up on the roof and a take away stall in the dome. Lots of information in the dome showing the history of the building.