A little bit of additional nitpicking:
When the user navigates away from the home page, you put an additional “Home” button in the bar on the left, which shifts the other buttons down. Then, when the user returns to the home page, you remove the “Home” button. The button appearance/disappearance is weird, and having buttons change position is a Bad Thing (you want to have the buttons stay in one place to support muscle memory).
You highlight the button for the page that the user is on, but there’s not enough visual contrast.
Consider merging the “Visiting” and “Location” sections. Remember, the user is trying to figure out how he can get to the museum, but you’re forcing him to go to two different pages to complete the task.
The application title bar shows the name of the page that the user is on (e.g., “Location”). This is a small enough web site that you don’t really need to do that–just use the “Clifford Road…” text.
Do you want to provide separate contact info for the webmaster?
Provide better alt text for the banner–use the “Clifford Road…” text, not just “Home”.
You have a big chunk of blank space at the upper left; it’s particularly noticeable if the user maximizes the window on a big monitor. Try moving the banner and navigation buttons up and to the left and see if that improves it.
Copy-edit the text (e.g., “use” on the Contact page; some punctuation issues)
On the Visiting page, see if you can get tighter leading between the lines for each month, but keep the larger space between the months. As it is, the lines just kinda visually run into each other.
On the Visiting page, under “Admission prices”, what are “Concessions”? If the usage here is the same as the American usage (i.e., food & drink), there’s no need to have that info on the web page. If you really want to have it there, at least move it out of the “Admission” section, since it’s not actually an admission price. (If the term means something else, of course, please disregard the previous comment.)
On the Contact page, see if you can clear the fields when the user first places focus in the field. Currently, the user has to place focus in the field, then click a few times to clear your sample text.
On the Contact page, you have the Telephone field highlighted in yellow. This typically indicates a required field, but I see no real reason why that info should be required.
On the Contact page, provide labels for the fields (“Name”, etc.) outside the fields themselves.
On the Contact page, if I type in a field, then navigate to a different page and return to the Contact page, the info is cleared. This is very low-pri, but it might be nice if you could persist the information.
