Some suggestions follow:
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Hotel Forum ****
http://www.hotelforum.com
Hotel Mercure ****
https://www.accorhotels.com/gb/hotel-2909-mercure-rome-colosseum-centre/index.shtml
Hotel Palatino ****
http://www.fhhotelgroup.it/en/grand-hotel-palatino-roma/index
Hotel Capo d'Africa ****
http://www.hotelcapodafrica.com/en
Hotel Fori Imperiali Cavalieri ***
http://www.hotelforiimperialicavalieri.com/en
Hotel Lancelot ***
http://www.lancelothotel.com
Hotel Edera ***
http://www.hotelederaroma.com/en
Hotel Raffaello ***
http://www.hotelraffaello.it/en
Hotel Romano **
http://www.hotelromano.it/en
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No agreement for pre-discounted rate has been signed.
To make your best choice you may also consider to refer to the following websites: