Just a little advertisement of my hometown as a vacation goal for steampunks...
There's an open air gaslamp museum in Tiergarten. It features various lamps, illustrating the history of gaslight in Berlin. Nearly every exhibit is in full working condition and hooked up to the gaslight system. Some of the exhibits are still in everyday use. The Charlottenburg chandeliers, for example, can still be found around Charlottenburg Palace.
Have some impressions.