Ok... I've been "told some facts" by a native Hawaiian...so here's the proper information:

First of all, the "Y" shaped building is not where Hawaii Five-O was filmed. The building in the picture is the Sheraton Waikiki Hotel (one of 4 Sheraton hotels in Waikiki.) Hawaii Five-O was filmed in a studio near Diamond head, but the shots of "headquarters" was always filmed at Iolani Palace.

Editor's note: What about when the helicopter flew towards a hotel where the main actor was on a balcony...that was the Sheraton wasn't it?

Next, the "pink" building you are referring to is The Royal Hawaiian hotel. It is very beautiful, but not the first hotel in Waikiki. The first hotel in Waikiki was the Moana Hotel (located right across from the Hyatt). These 2 hotels are also owned and operated by the Sheraton chain.

Editor's note: Oh, you mean the one kitty corner to the Hyatt! Where that bamboo shopping mall is! Got a picture of it. Across from the Hyatt is the beach...see picture below!

The hospitality room where we had breakfast and dinner had an excellent view.
Notice the "pink" hotel near the center bottom, the Royal Hawaiian.
That was the first hotel on Waikiki beach, but correct me if I'm wrong on that information.
Also the tall building behind it, shaped like a "Y" is the Hilton
(I believe where the original Hawaii 5-0 was filmed.)

The Aloha clock tower in Pearl Harbor...many a sailor knows this landmark.

Thirdly, the "clock tower is really called Aloha Tower and is located at the entrance to Honolulu Harbor. At one time, this was the tallest building in Hawaii. Aloha Tower is now a major attraction as the city has developed it in to the Aloha Tower Marketplace. There are many shops and restaurants there.

Buddy, that was a good try to being "tour guide", but I think you should come and visit again and let me give you an official tour of my island. 

Thanks for the laughs...but try to change it. I don't think the visitor's Bureau would appreciate the mix-up! :)

Waikiki beach was just across the street from our Hotel!
Did you know that the sand on Waikiki beach had to be trucked in?  Yep. They brought countless dump trucks of sand from the east side of the island.