Hi della, the first sentence sounds native but too complex (and with a grammar error with the use of the word "its." The 2nd sentence has grammar issues. The 3rd sentence has grammar issues, and I'm not clear what the meaning should be. This is probably better discussed in your notebook, but I will try here. Just so you know, it's considered weak writing to use so many adjectives, especially in a row, although I imagine it is good practice for your vocabulary. Here is my rewrite:
During my one month study in the UK the summer of my freshman year, I fell in love with the ancient, unsophisticated castles and the formidable, gothic churches of Scotland. They bear witness to the vicissitudes of history and Scotland's profound culture (note: 'profound' doesn't work well here but it kind of makes sense a little). The architecture of UK universities is totally different from America's (note: the subject/verb agreement here sounds weird, but it is grammatically correct. But about half the population would probably use "are" instead of "is" even though it's incorrect to do so).
The museums look like they grew naturally from the ground, like excavated pottery.