Walk around central london and it will feel like there is a famous landmark on every corner.
The following links take you to a page with information on various places, palaces, memorials, houses, landmarks, buildings and even the odd cemetery that make up historical and modern day london (the list is in alphabetical order):
Admiralty Arch
Albert Memorial
Apsely House (The Wellington Museum) (admission charges)
Bank of England / Museum
Banqueting House (admission charges)
Bunhill Fields Non Conformist Cemetery
Carlyle's House (admission charges)
Cenotaph, the
Central Criminal Court (Old Bailey)
Central Hall
Chiswick House (admission charges)
Clarence House (admission charges)
Cleopatra's Needle
Commonwealth Institute
County Hall (home to the london eye, london acquarium and saatchi gallery)
Downing Street (not open to the public, you cannot see the door to number 10 from the gates)
Duke of Yorks Column
Ely Place (St Ehtelreda's Church)
Goldsmiths Hall (occasional open days only)
Grays Inn
Guildhall
Kenwood House
Lambeth Palace (occasional tours, only with prior arrangement)
Leadenhall Market
Lincolns Inn
Lloyds Building
Lombard Street
London Bridge
London Stone
London Telecom Tower
Mansion House (tours only with prior arrangement)
Marble Arch
Marlborough House (tours only with prior arrangement)
The Monument (admission charges)
Natural History Museum
New Scotland Yard (not open to the public, but you can see the 3 sided sign)
The Oratory Church
Piccadilly Circus & Eros
Queen Victoria Memorial
Roman Bath (limited opening times, small admission charge)
Roosevelt Memorial
Royal Albert Hall (daily tours, admission charges)