How to positively describe something, such as a war memorial, which doesn't invoke positive feelings?

Solution 1:

The verb moving can be put to service here.

From http://dictionary.reference.com/browse/moving:

stirring or evoking strong feelings or emotions, especially touchingly or pathetically

"The war memorial was a moving experience."

Solution 2:

You could consider using memorable:

Worth remembering or easily remembered, especially because of being special or unusual.

Or impressive:

Evoking admiration through size, quality, or skill; grand, imposing, or awesome

[Oxford Online Dictionary]