1. Eiffel Tower: At 1,040 feet tall, the tower is one of the "most recognizable structures in the world."Frommer's: Eiffel Tower Concierge.com calls it a "fascinating" work of architecture, and the "quintessential symbol" of Paris.Concierge.com: Eiffel Tower
2. Arc de Triomphe: 12 avenues intersect at this 19th Century structure, also home to the Tomb of the Unknown Soldier underneath.Lonely Planet: Arc de Triomphe Visitors can climb the Arc for "amazing" views of Paris.Fodor's: Paris Top Attractions
3. Notre-Dame: Considered a "great Gothic masterpiece" and a "moving" Christian structure, this cathedral features gargoyles along its towers.Concierge.com: Notre-Dame de Paris
4. Louvre: Often seen as the "grandest museum in the world," the showcased artwork includes the Mona Lisa and Venus de Milo.Fodor's: Paris Top Attractions
5. Sacré-Coeur: A "well-loved" landmark in Paris, the basilica domes offer a "spectacular" panoramic view of the city.Lonely Planet: Basilique du Sacré-Cœur

Fodor's presents several themed itineraries. One focuses on the top Paris monuments, and another points out the popular palaces and mansions around town. Fodor's also has an itinerary for travelers who just want to shop.Fodor's: Paris Great Itineraries