There is one church in Lima that might be worth seeing. It's very close to downtown and any cab driver will know what you're talking about. I think it might be St. Mary's but not for certain.
The catacombs in that church are quite impressive if you're into the macabre. There a very cheap on-going guided tours in several different languages. Other than that, the large church is a terrific example on the Spanish influence on Peru's history. Just be sure you try to negotiate the cab fare before he takes you if you take a cab.
Cuzco is a WONDERRUL city full of rich culture and cobbled streets. It's very different from Lima where mysterious ruins and awesome mountain views abound.
The only thing bad I have to say about my experience is the fact that motorists, namely the cabbies, use their horns to communicate, constantly. Literally every second someone is honking their horn. It's quite fascinating really, but can get downright annoying if you've just spent five days hiking the Inca Trail to Machu Pichu and your first night in a real bed is fraught with - **BEEP**BEEP**BEEP***BEEP BEEP**BEEP**BEEP**BEEP, well you get the idea.
A number of hotels have nice balconies that overlook the several main squares. We were able to negotiate a very reasonable price once we arrived. Deffinetly plan on walking the squares to find great authentic Cetchua souvenirs.
If you haven't heard of it, if you do go to Machu Pichu you will experience the little town of Aguas Calientes. The train runs right in the middle of everything, but the town itself is quaint and very likable. Modern little jewelry shops are nestled against many nice (and some not so nice) restaurants and cantinas catering to the bustle of tourists. Take in the hot springs, they are very cheap and the short hike along the river to them has recently been refurbished. (Just don't go if you have any open sores!) Otherwise they are quite healthy. Buy a beer and take a relaxing soak!
Just a couple of tips for you. I really enjoyed my time in Peru. Before Cuzco, I spent a week on the Amazon. If you ever get a chance to do that, do. It's a life-altering experience. I loved it.
Safe journeys!
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Life is a book. Never travel and you are reading only one page.l