A couple weeks ago we took Xander to the Denver Museum of Nature & Science. The actual museum itself is rather large, taking up three stories and covering everything from space to natural history. I enjoyed all the exhibits, but with a 18 month old you tend to blast through everything. We managed to get Xander to sit through a black hole movie inside their sweet planetarium. I will definitely be going back again for a more thorough walk-through (and IMAX).