I found an opportunity to visit Frederic C. Robie House in Chicago recently, which was my third visited building for this property. True to the inscription, the house exhibits discernible elements of “organic architecture” and a number of techniques and solutions that mark Frank Lloyd Wright as one of the foremost innovators of the 20th century in his field. And yet it is somewhat underwhelming once you step inside. There are lovely partially stained-glass windows throughout, notable built-in features doubling as decorative elements, and examples of impressive masonry echoing the exterior, but the relative emptiness of the house mutes the impression quite a bit.

Enthusiastic students of architecture - especially of its modern history - will certainly get significant value out of visiting Robie House. The guide provides a lot of context, historical nuggets, and rationale behind architectural decisions to make it worthwhile. Visually, Guggenheim and Fallingwater are degrees of magnitude more impressive. Even Kentuck Knob, which is not part of the WH inscription, retains a bigger visual impression in my memory a good decade after my trip there.

Robie House can be reached from the Chicago Loop area in under an hour by public transport – or in about 15 minutes by car. Guided tours run throughout the day, starting every half hour and lasting about 45 minutes. Advanced reservations are required these days.

When it comes to Guggenheim, it is my "hometown" sight - I have visited it many times over the years, most recently a couple of months ago. The striking white spiral of the museum is practically unmissable for any New York visitor - you will surely find yourself on the Museum Mile, either on foot or in a double-decker tourist bus at some point during your stay in New York City. During the most popular exhibitions, at peak times there may be lines to enter the building, but if you manage to walk in, you can admire the interior from the ground floor entirely for free, since the tickets are checked only at the foot of the spiraling ramp - and you don't have to walk up the ramp to get a good appreciation of the structure. (Coincidentally, I happen to think that Guggenheim rarely delivers reasonable value for money when it comes to its changing exhibitions - being a corporate member with free access definitely helps me in this regard; for a short-time visit to the city, I would not recommend making Guggenheim one of your art-museum-going targets).

I also visited Fallingwater in rural Pennsylvania several years ago. The house is just stunning in its design and the way it takes advantage of its natural setting. It is also colorfully furnished and appears very livable. You can only enter with a guided tour at predefined times, so plan well in advance. (Not listed on this inscription Kentuck Knob is close enough that you can combine the two visits into a single half-day, if you are so inclined.)

On my limited evidence, Wright Buildings compare favorably to the works of Horta or Le Corbusier. Wright's innovative impact is probably enough to justify OUV of this property, and certainly at least some of the included buildings are true masterpieces.