When most people think of the architecture in the United Kingdom, they visualise ancient stone castles and historic landmarks where famous battles were once fought. These are structures that the UK does offer and they are for the most part available for tourists to visit anytime. There are also, however, some fairly impressive modern buildings in the UK, including some very tall office towers with fairly hefty business gas bills. The London skyline, once kept low so as not to overpower historic castles and cathedrals, has risen a few hundred feet more above sea level in recent years.