Most of the other locations on this list are great because they offer a level of discretion. The Natural History Museum is a perfect place to hook-up because you can have your fun in plain sight. Sure, you can post up behind a wooly mammoth or dinosaur skeleton, but why not sneak your lady into the indigenous people's display and act as though you are just part of the exhibit? You'll commune with history as you warm yourselves next our anceint ancestors first attempt at fire. We recommend waiting until the weekend to try this time travelling adventure. If you get caught during the week, it will likely be by school children on field trips. If you're freaky activity is discovered on the weekend, it it will likely be by a visiting couple in search of culture, and the resulting charges will be less severe.