It's just about 150 from Pune to Mumbai. Looks really close. Especially on train. Should be like a flash. Though it's not that easy. Something went wrong from the very beginning.
On the ticket counter there were two types of windows: fast queue and slow queue. So it was obvious for us that we have to go in a quick one. We already had a paper with all the details like we already did in Agra. However it turned out that the paper is not needed, and the ticket price was much cheaper than we expected to be (we checked it in internet in advance). Just 90 rupees (about 1.2 Euro) per person. It already was suspicious, but we had no time to figure out what happened as the train was about to depart according to schedule.

So we made 2 mistakes: trusted the schedule and bought wrong tickets. The train arrived to the station just half an hour later, than was scheduled. And the tickets were just a basic tickets with no place reserved. So we had to stay, while there was no free seat available.
The train car is also interesting. Of course there was no AC (no surprise). A huge fans installed through all the space, all windows are open. Ah, well, and doors also are open. Even when the train goes full speed. People stay in the doors or even put legs outside while train is going. Safety as it is (:

Add there that it was a last train before a huge gap (for several hours) Friday evening. Everybody wants to be in time for this train, so there was a lot of people. It was hard to find a place even to stay. Also all the way some food sellers sneak around in the train car. You can buy there food, tea and other spicy stuff. Some food is already wrapped in nice package, some they mix right in front of you. With the same hands they used to hold a money a moment ago. And they go through the car really often.

The train goes really slow. The trip took 4.5 hours. Four and a half hours! First two hours we had to stay. And yet they call this train superfast. SUPERFAST (!) The average speed is about 35 km per hour.

On train stations there are a lot of people who sleep there or simply waits. Looks like their train is late not for just half an hour. These people are waiting with huge bags. Some put sheets to sleep, some sleep right on the floor. I've never seen anything like that before. (these pictures are just a "light" version, didn't manage to take a picture right on the Pune train station).

Mumbai met us with unexpected trash everywhere and strange smell like on a scrap-heap. It might be caused by recent flood which took place here a couple of weeks ago. To be honest, it didn't seem to me that it's related.

Mumbai was the first city in India where I felt myself like in a big city. There are way too many skyscrapers, more or less civil traffic. Nevertheless there are still cows in the city. It's everywhere :)

English heritage is easily spotted here. A lot of buildings are built in English style or by their projects.

Court building is secured by military guys in such booths. They have long-gun and order do not take photos here.

We started the walk quite early in the morning, so we saw a lot of sleeping people right on the streets.

In local library we saw a funny moment, where the guy hit the monument with rag (looks like he wanted to clean the dust). However he did it with extremely serious face, thus it looked really funny.

By the way, Mumbai is located on the island. Could you imagine that?

Right on the seaside, next to India gate (yes, just like in Delhi) they feed pigeons. And put a lot of food for them.
There are a lot of birds there. Feels like local San Marco square.

The water is really dirty (still can't get used to it). Next to this place a beautiful couple takes pictures. But they won't have this trash on their photos.

Nearby there is The Taj Mahal Palace Hotel. According to legend it was built by Tata because he was refused to enter one of grand hotels in Mumbai, where only whites were allowed. So he wanted to equalize the rights. Also you might remember the hotel from breaking news in 2008, when several hundreds people were held as hostages here.

To some temples the way lays on quite narrow streets.

Haji Ali Darga mosque was built in 0.5 km from the seaside. On the water. During high water you might not reach the mosque.

I've heard that at Fridays around 40 thousands prayers visit the mosque.

Meanwhile a very strong rain begun. So we were absolutely wet before we reached the next stop.

F huge laundry under open air. Dhobi Ghat. In the rain obviously nobody washes the clothes (well, with some exceptions), but it's all done manually. Up to 1000 clothes per person. Unbelievable.

Of course, it's not the entire Mumbai, but only a small part of it. There are also famous slums, which we didn't reach (well, I'm not sure if it's a good idea from safety point of view), a lot of other notable sights, but we simply didn't have enough time. Maybe at other occasion. PS. Just in case, if you still have doubts, Mumbai and Bombay is the same city. Bombay was renamed to Mumbai just in 1994. Not so far away.